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-rw-r--r--develop/404.html15
-rw-r--r--develop/CAPTCHA_SETUP.html15
-rw-r--r--develop/admin_api/account_validity.html15
-rw-r--r--develop/admin_api/event_reports.html15
-rw-r--r--develop/admin_api/experimental_features.html15
-rw-r--r--develop/admin_api/media_admin_api.html15
-rw-r--r--develop/admin_api/purge_history_api.html15
-rw-r--r--develop/admin_api/register_api.html15
-rw-r--r--develop/admin_api/room_membership.html15
-rw-r--r--develop/admin_api/rooms.html15
-rw-r--r--develop/admin_api/server_notices.html15
-rw-r--r--develop/admin_api/statistics.html15
-rw-r--r--develop/admin_api/user_admin_api.html15
-rw-r--r--develop/admin_api/version_api.html15
-rw-r--r--develop/application_services.html15
-rw-r--r--develop/auth_chain_difference_algorithm.html15
-rw-r--r--develop/code_style.html15
-rw-r--r--develop/consent_tracking.html15
-rw-r--r--develop/delegate.html15
-rw-r--r--develop/deprecation_policy.html15
-rw-r--r--develop/development/cas.html15
-rw-r--r--develop/development/contributing_guide.html15
-rw-r--r--develop/development/database_schema.html15
-rw-r--r--develop/development/demo.html15
-rw-r--r--develop/development/dependencies.html15
-rw-r--r--develop/development/experimental_features.html15
-rw-r--r--develop/development/git.html15
-rw-r--r--develop/development/internal_documentation/index.html15
-rw-r--r--develop/development/releases.html15
-rw-r--r--develop/development/reviews.html15
-rw-r--r--develop/development/room-dag-concepts.html15
-rw-r--r--develop/development/saml.html15
-rw-r--r--develop/development/synapse_architecture/cancellation.html15
-rw-r--r--develop/development/synapse_architecture/faster_joins.html15
-rw-r--r--develop/development/synapse_architecture/streams.html15
-rw-r--r--develop/docs/website_files/version-picker.css78
-rw-r--r--develop/docs/website_files/version-picker.js127
-rw-r--r--develop/docs/website_files/version.js1
-rw-r--r--develop/federate.html15
-rw-r--r--develop/index.html15
-rw-r--r--develop/jwt.html15
-rw-r--r--develop/log_contexts.html15
-rw-r--r--develop/manhole.html15
-rw-r--r--develop/media_repository.html15
-rw-r--r--develop/message_retention_policies.html15
-rw-r--r--develop/metrics-howto.html15
-rw-r--r--develop/modules/account_data_callbacks.html15
-rw-r--r--develop/modules/account_validity_callbacks.html15
-rw-r--r--develop/modules/add_extra_fields_to_client_events_unsigned.html15
-rw-r--r--develop/modules/background_update_controller_callbacks.html15
-rw-r--r--develop/modules/index.html15
-rw-r--r--develop/modules/password_auth_provider_callbacks.html15
-rw-r--r--develop/modules/porting_legacy_module.html15
-rw-r--r--develop/modules/presence_router_callbacks.html15
-rw-r--r--develop/modules/spam_checker_callbacks.html15
-rw-r--r--develop/modules/third_party_rules_callbacks.html15
-rw-r--r--develop/modules/writing_a_module.html15
-rw-r--r--develop/openid.html15
-rw-r--r--develop/opentracing.html15
-rw-r--r--develop/other/running_synapse_on_single_board_computers.html15
-rw-r--r--develop/password_auth_providers.html15
-rw-r--r--develop/postgres.html15
-rw-r--r--develop/print.html15
-rw-r--r--develop/replication.html15
-rw-r--r--develop/reverse_proxy.html15
-rw-r--r--develop/room_and_user_statistics.html15
-rw-r--r--develop/server_notices.html15
-rw-r--r--develop/setup/forward_proxy.html15
-rw-r--r--develop/setup/installation.html15
-rw-r--r--develop/setup/turn/coturn.html15
-rw-r--r--develop/setup/turn/eturnal.html15
-rw-r--r--develop/sso_mapping_providers.html15
-rw-r--r--develop/structured_logging.html15
-rw-r--r--develop/synctl_workers.html15
-rw-r--r--develop/systemd-with-workers/index.html15
-rw-r--r--develop/tcp_replication.html15
-rw-r--r--develop/templates.html15
-rw-r--r--develop/turn-howto.html15
-rw-r--r--develop/upgrade.html15
-rw-r--r--develop/usage/administration/admin_api/background_updates.html15
-rw-r--r--develop/usage/administration/admin_api/federation.html15
-rw-r--r--develop/usage/administration/admin_api/index.html15
-rw-r--r--develop/usage/administration/admin_api/registration_tokens.html15
-rw-r--r--develop/usage/administration/admin_faq.html15
-rw-r--r--develop/usage/administration/database_maintenance_tools.html15
-rw-r--r--develop/usage/administration/index.html15
-rw-r--r--develop/usage/administration/monitoring/reporting_homeserver_usage_statistics.html15
-rw-r--r--develop/usage/administration/monthly_active_users.html15
-rw-r--r--develop/usage/administration/request_log.html15
-rw-r--r--develop/usage/administration/state_groups.html15
-rw-r--r--develop/usage/administration/understanding_synapse_through_grafana_graphs.html15
-rw-r--r--develop/usage/administration/useful_sql_for_admins.html15
-rw-r--r--develop/usage/configuration/config_documentation.html15
-rw-r--r--develop/usage/configuration/homeserver_sample_config.html15
-rw-r--r--develop/usage/configuration/index.html15
-rw-r--r--develop/usage/configuration/logging_sample_config.html15
-rw-r--r--develop/usage/configuration/user_authentication/index.html15
-rw-r--r--develop/usage/configuration/user_authentication/refresh_tokens.html15
-rw-r--r--develop/usage/configuration/user_authentication/single_sign_on/cas.html15
-rw-r--r--develop/usage/configuration/user_authentication/single_sign_on/index.html15
-rw-r--r--develop/usage/configuration/user_authentication/single_sign_on/saml.html15
-rw-r--r--develop/user_directory.html15
-rw-r--r--develop/website_files/theme/index.hbs12
-rw-r--r--develop/website_files/version-picker.css78
-rw-r--r--develop/website_files/version-picker.js127
-rw-r--r--develop/website_files/version.js1
-rw-r--r--develop/welcome_and_overview.html15
-rw-r--r--develop/workers.html15
108 files changed, 1939 insertions, 0 deletions
diff --git a/develop/404.html b/develop/404.html
index 9d2b63f465..a873fd80e7 100644
--- a/develop/404.html
+++ b/develop/404.html
@@ -29,6 +29,7 @@
         <link rel="stylesheet" href="docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -104,6 +105,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -173,5 +186,7 @@
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/CAPTCHA_SETUP.html b/develop/CAPTCHA_SETUP.html
index 879a3289f3..c6fea177ec 100644
--- a/develop/CAPTCHA_SETUP.html
+++ b/develop/CAPTCHA_SETUP.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -220,5 +233,7 @@ listeners section of the <code>homeserver.yaml</code> configuration file.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/admin_api/account_validity.html b/develop/admin_api/account_validity.html
index 3f97284c26..61ef5d106a 100644
--- a/develop/admin_api/account_validity.html
+++ b/develop/admin_api/account_validity.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -215,5 +228,7 @@ milliseconds since epoch:</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/admin_api/event_reports.html b/develop/admin_api/event_reports.html
index fd2121e896..f03edc4926 100644
--- a/develop/admin_api/event_reports.html
+++ b/develop/admin_api/event_reports.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -348,5 +361,7 @@ will be an empty JSON object.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/admin_api/experimental_features.html b/develop/admin_api/experimental_features.html
index 00b32d6429..54e603adcc 100644
--- a/develop/admin_api/experimental_features.html
+++ b/develop/admin_api/experimental_features.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -226,5 +239,7 @@ user like so:</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/admin_api/media_admin_api.html b/develop/admin_api/media_admin_api.html
index 0180aa291e..a843c4ee05 100644
--- a/develop/admin_api/media_admin_api.html
+++ b/develop/admin_api/media_admin_api.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -403,5 +416,7 @@ from the originating server.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/admin_api/purge_history_api.html b/develop/admin_api/purge_history_api.html
index c40eedfa0d..ca66fb8a3a 100644
--- a/develop/admin_api/purge_history_api.html
+++ b/develop/admin_api/purge_history_api.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -234,5 +247,7 @@ a purge id:</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/admin_api/register_api.html b/develop/admin_api/register_api.html
index af44e600ef..bf59e2152d 100644
--- a/develop/admin_api/register_api.html
+++ b/develop/admin_api/register_api.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -260,5 +273,7 @@ def generate_mac(nonce, user, password, admin=False, user_type=None):
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/admin_api/room_membership.html b/develop/admin_api/room_membership.html
index 1db4204bba..2be741341c 100644
--- a/develop/admin_api/room_membership.html
+++ b/develop/admin_api/room_membership.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -211,5 +224,7 @@ for a server admin: see <a href="../usage/administration/admin_api/">Admin API</
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/admin_api/rooms.html b/develop/admin_api/rooms.html
index 52a771811d..51eea394b8 100644
--- a/develop/admin_api/rooms.html
+++ b/develop/admin_api/rooms.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -1139,5 +1152,7 @@ that were deleted.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/admin_api/server_notices.html b/develop/admin_api/server_notices.html
index 8f2b92417f..5ab224ffb4 100644
--- a/develop/admin_api/server_notices.html
+++ b/develop/admin_api/server_notices.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -216,5 +229,7 @@ can be used. See <a href="../server_notices.html">the server notices documentati
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/admin_api/statistics.html b/develop/admin_api/statistics.html
index 2b5f94d187..3c0349a437 100644
--- a/develop/admin_api/statistics.html
+++ b/develop/admin_api/statistics.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -295,5 +308,7 @@ in the database.</li>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/admin_api/user_admin_api.html b/develop/admin_api/user_admin_api.html
index 163a09d364..35d4339609 100644
--- a/develop/admin_api/user_admin_api.html
+++ b/develop/admin_api/user_admin_api.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -1345,5 +1358,7 @@ for more information.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/admin_api/version_api.html b/develop/admin_api/version_api.html
index d2b3817223..e2d5d8db15 100644
--- a/develop/admin_api/version_api.html
+++ b/develop/admin_api/version_api.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -200,5 +213,7 @@ response body.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/application_services.html b/develop/application_services.html
index 910777f19e..f09ec0caa1 100644
--- a/develop/application_services.html
+++ b/develop/application_services.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -212,5 +225,7 @@ namespaces:
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/auth_chain_difference_algorithm.html b/develop/auth_chain_difference_algorithm.html
index 1acefd678e..a7de274eee 100644
--- a/develop/auth_chain_difference_algorithm.html
+++ b/develop/auth_chain_difference_algorithm.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -306,5 +319,7 @@ level).</li>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/code_style.html b/develop/code_style.html
index 70323b243f..0778a05b37 100644
--- a/develop/code_style.html
+++ b/develop/code_style.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -304,5 +317,7 @@ is left as an exercise for the reader!</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/consent_tracking.html b/develop/consent_tracking.html
index abe5ded164..ef9e43881c 100644
--- a/develop/consent_tracking.html
+++ b/develop/consent_tracking.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -346,5 +359,7 @@ URI that clients use to connect to the server. (It is used to construct
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/delegate.html b/develop/delegate.html
index 20f1fcdd3f..81d226bee7 100644
--- a/develop/delegate.html
+++ b/develop/delegate.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -265,5 +278,7 @@ reverse proxy.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/deprecation_policy.html b/develop/deprecation_policy.html
index cf8713a6b4..bc836af7d6 100644
--- a/develop/deprecation_policy.html
+++ b/develop/deprecation_policy.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -223,5 +236,7 @@ and is consistent with the <code>.deb</code> packages released by Matrix.org.</p
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/development/cas.html b/develop/development/cas.html
index 0175828eac..e612d484c0 100644
--- a/develop/development/cas.html
+++ b/develop/development/cas.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -247,5 +260,7 @@ and that the CAS server is on port 8000, both on localhost.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/development/contributing_guide.html b/develop/development/contributing_guide.html
index 5c61bb26cd..47a19466d7 100644
--- a/develop/development/contributing_guide.html
+++ b/develop/development/contributing_guide.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -638,5 +651,7 @@ do!</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/development/database_schema.html b/develop/development/database_schema.html
index 0aeae50c98..b40431e587 100644
--- a/develop/development/database_schema.html
+++ b/develop/development/database_schema.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -517,5 +530,7 @@ SCHEMA_COMPAT_VERSION = S + 4 # we can't roll back to a time before old_column w
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/development/demo.html b/develop/development/demo.html
index ce8e259aa1..ab4680e4ed 100644
--- a/develop/development/demo.html
+++ b/develop/development/demo.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -220,5 +233,7 @@ name.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/development/dependencies.html b/develop/development/dependencies.html
index b4aecc2a51..300866c0dd 100644
--- a/develop/development/dependencies.html
+++ b/develop/development/dependencies.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -402,5 +415,7 @@ letting Poetry do the right thing.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/development/experimental_features.html b/develop/development/experimental_features.html
index bf06f62e93..d93390ddd9 100644
--- a/develop/development/experimental_features.html
+++ b/develop/development/experimental_features.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -218,5 +231,7 @@ configuration key (see the <code>synapse.config.experimental</code> file) and ei
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/development/git.html b/develop/development/git.html
index 34b9fb0ee3..c7edcafa67 100644
--- a/develop/development/git.html
+++ b/develop/development/git.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -306,5 +319,7 @@ the history of Synapse), we've had two releases in flight at once. Obviously,
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/development/internal_documentation/index.html b/develop/development/internal_documentation/index.html
index 51262280eb..ce53acd347 100644
--- a/develop/development/internal_documentation/index.html
+++ b/develop/development/internal_documentation/index.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -194,5 +207,7 @@ under the Usage section of the documentation.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/development/releases.html b/develop/development/releases.html
index 30981828af..4c6f7d27cd 100644
--- a/develop/development/releases.html
+++ b/develop/development/releases.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -215,5 +228,7 @@ found in the <a href="https://matrix.org/category/security">security category of
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/development/reviews.html b/develop/development/reviews.html
index c30202f86f..1f1277436a 100644
--- a/develop/development/reviews.html
+++ b/develop/development/reviews.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -218,5 +231,7 @@ with the rationale on why you're putting it back in the queue.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/development/room-dag-concepts.html b/develop/development/room-dag-concepts.html
index 099a644e13..0b524d6328 100644
--- a/develop/development/room-dag-concepts.html
+++ b/develop/development/room-dag-concepts.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -274,5 +287,7 @@ notes from @Azrenbeth, https://pastebin.com/seUGVGeT</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/development/saml.html b/develop/development/saml.html
index 3e3b9fb124..b2dfb316a7 100644
--- a/develop/development/saml.html
+++ b/develop/development/saml.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -223,5 +236,7 @@ samling page and clear the site data. In Chrome, this will be a button on the Ap
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/development/synapse_architecture/cancellation.html b/develop/development/synapse_architecture/cancellation.html
index 097990e4a2..d0d21dd153 100644
--- a/develop/development/synapse_architecture/cancellation.html
+++ b/develop/development/synapse_architecture/cancellation.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -532,5 +545,7 @@ with LoggingContext(&quot;request-1&quot;):
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/development/synapse_architecture/faster_joins.html b/develop/development/synapse_architecture/faster_joins.html
index f43f49a007..1ef1606f41 100644
--- a/develop/development/synapse_architecture/faster_joins.html
+++ b/develop/development/synapse_architecture/faster_joins.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -526,5 +539,7 @@ work?</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/development/synapse_architecture/streams.html b/develop/development/synapse_architecture/streams.html
index b940cdf006..4edb971b82 100644
--- a/develop/development/synapse_architecture/streams.html
+++ b/develop/development/synapse_architecture/streams.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -318,5 +331,7 @@ nowadays it's done via Redis's Pubsub.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/docs/website_files/version-picker.css b/develop/docs/website_files/version-picker.css
new file mode 100644
index 0000000000..28e5d5219a
--- /dev/null
+++ b/develop/docs/website_files/version-picker.css
@@ -0,0 +1,78 @@
+.version-picker {
+    display: flex;
+    align-items: center;
+}
+
+.version-picker .dropdown {
+    width: 130px;
+    max-height: 29px;
+    margin-left: 10px;
+    display: inline-block;
+    border-radius: 4px;
+    border: 1px solid var(--theme-popup-border);
+    position: relative;
+    font-size: 13px;
+    color: var(--fg);
+    height: 100%;
+    text-align: left;
+}
+.version-picker .dropdown .select {
+    cursor: pointer;
+    display: block;
+    padding: 5px 2px 5px 15px;
+}
+.version-picker .dropdown .select > i {
+    font-size: 10px;
+    color: var(--fg);
+    cursor: pointer;
+    float: right;
+    line-height: 20px !important;
+}
+.version-picker .dropdown:hover {
+    border: 1px solid var(--theme-popup-border);
+}
+.version-picker .dropdown:active {
+    background-color: var(--theme-popup-bg);
+}
+.version-picker .dropdown.active:hover,
+.version-picker .dropdown.active {
+    border: 1px solid var(--theme-popup-border);
+    border-radius: 2px 2px 0 0;
+    background-color: var(--theme-popup-bg);
+}
+.version-picker .dropdown.active .select > i {
+    transform: rotate(-180deg);
+}
+.version-picker .dropdown .dropdown-menu {
+    position: absolute;
+    background-color: var(--theme-popup-bg);
+    width: 100%;
+    left: -1px;
+    right: 1px;
+    margin-top: 1px;
+    border: 1px solid var(--theme-popup-border);
+    border-radius: 0 0 4px 4px;
+    overflow: hidden;
+    display: none;
+    max-height: 300px;
+    overflow-y: auto;
+    z-index: 9;
+}
+.version-picker .dropdown .dropdown-menu li {
+    font-size: 12px;
+    padding: 6px 20px;
+    cursor: pointer;
+} 
+.version-picker .dropdown .dropdown-menu {
+    padding: 0;
+    list-style: none;
+}
+.version-picker .dropdown .dropdown-menu li:hover {
+    background-color: var(--theme-hover);
+}
+.version-picker .dropdown .dropdown-menu li.active::before {
+    display: inline-block;
+    content: "✓";
+    margin-inline-start: -14px;
+    width: 14px;
+}
\ No newline at end of file
diff --git a/develop/docs/website_files/version-picker.js b/develop/docs/website_files/version-picker.js
new file mode 100644
index 0000000000..bb35a7d896
--- /dev/null
+++ b/develop/docs/website_files/version-picker.js
@@ -0,0 +1,127 @@
+
+const dropdown = document.querySelector('.version-picker .dropdown');
+const dropdownMenu = dropdown.querySelector('.dropdown-menu');
+
+fetchVersions(dropdown, dropdownMenu).then(() => {
+    initializeVersionDropdown(dropdown, dropdownMenu);
+});
+
+/**
+ * Initialize the dropdown functionality for version selection.
+ * 
+ * @param {Element} dropdown - The dropdown element.
+ * @param {Element} dropdownMenu - The dropdown menu element.
+ */
+function initializeVersionDropdown(dropdown, dropdownMenu) {
+    // Toggle the dropdown menu on click
+    dropdown.addEventListener('click', function () {
+        this.setAttribute('tabindex', 1);
+        this.classList.toggle('active');
+        dropdownMenu.style.display = (dropdownMenu.style.display === 'block') ? 'none' : 'block';
+    });
+  
+    // Remove the 'active' class and hide the dropdown menu on focusout
+    dropdown.addEventListener('focusout', function () {
+        this.classList.remove('active');
+        dropdownMenu.style.display = 'none';
+    });
+  
+    // Handle item selection within the dropdown menu
+    const dropdownMenuItems = dropdownMenu.querySelectorAll('li');    
+    dropdownMenuItems.forEach(function (item) {
+        item.addEventListener('click', function () {
+            dropdownMenuItems.forEach(function (item) {
+                item.classList.remove('active');
+            });
+            this.classList.add('active');
+            dropdown.querySelector('span').textContent = this.textContent;
+            dropdown.querySelector('input').value = this.getAttribute('id');
+
+            window.location.href = changeVersion(window.location.href, this.textContent);
+        });
+    });
+};
+
+/**
+ * This function fetches the available versions from a GitHub repository
+ * and inserts them into the version picker.
+ * 
+ * @param {Element} dropdown - The dropdown element.
+ * @param {Element} dropdownMenu - The dropdown menu element.
+ * @returns {Promise<Array<string>>} A promise that resolves with an array of available versions.
+ */
+function fetchVersions(dropdown, dropdownMenu) {
+    return new Promise((resolve, reject) => {
+        window.addEventListener("load", () => {
+
+            fetch("https://api.github.com/repos/matrix-org/synapse/git/trees/gh-pages", {
+                cache: "force-cache",
+            }).then(res => 
+                res.json()
+            ).then(resObject => {
+                const excluded = ['dev-docs', 'v1.91.0', 'v1.80.0', 'v1.69.0'];
+                const tree = resObject.tree.filter(item => item.type === "tree" && !excluded.includes(item.path));
+                const versions = tree.map(item => item.path).sort(sortVersions);
+
+                // Create a list of <li> items for versions
+                versions.forEach((version) => {
+                    const li = document.createElement("li");
+                    li.textContent = version;
+                    li.id = version;
+    
+                    if (window.SYNAPSE_VERSION === version) {
+                        li.classList.add('active');
+                        dropdown.querySelector('span').textContent = version;
+                        dropdown.querySelector('input').value = version;
+                    }
+    
+                    dropdownMenu.appendChild(li);
+                });
+
+                resolve(versions);
+
+            }).catch(ex => {
+                console.error("Failed to fetch version data", ex);
+                reject(ex);
+            })
+        });
+    });
+}
+
+/**
+ * Custom sorting function to sort an array of version strings.
+ *
+ * @param {string} a - The first version string to compare.
+ * @param {string} b - The second version string to compare.
+ * @returns {number} - A negative number if a should come before b, a positive number if b should come before a, or 0 if they are equal.
+ */
+function sortVersions(a, b) {
+    // Put 'develop' and 'latest' at the top
+    if (a === 'develop' || a === 'latest') return -1;
+    if (b === 'develop' || b === 'latest') return 1;
+
+    const versionA = (a.match(/v\d+(\.\d+)+/) || [])[0];
+    const versionB = (b.match(/v\d+(\.\d+)+/) || [])[0];
+
+    return versionB.localeCompare(versionA);
+}
+
+/**
+ * Change the version in a URL path.
+ *
+ * @param {string} url - The original URL to be modified.
+ * @param {string} newVersion - The new version to replace the existing version in the URL.
+ * @returns {string} The updated URL with the new version.
+ */
+function changeVersion(url, newVersion) {
+    const parsedURL = new URL(url);
+    const pathSegments = parsedURL.pathname.split('/');
+  
+    // Modify the version
+    pathSegments[2] = newVersion;
+
+    // Reconstruct the URL
+    parsedURL.pathname = pathSegments.join('/');
+  
+    return parsedURL.href;
+}
\ No newline at end of file
diff --git a/develop/docs/website_files/version.js b/develop/docs/website_files/version.js
new file mode 100644
index 0000000000..6279bc07bf
--- /dev/null
+++ b/develop/docs/website_files/version.js
@@ -0,0 +1 @@
+window.SYNAPSE_VERSION = "develop";
diff --git a/develop/federate.html b/develop/federate.html
index 07c3688f0f..408261d48c 100644
--- a/develop/federate.html
+++ b/develop/federate.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -238,5 +251,7 @@ useful just for development purposes. See
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/index.html b/develop/index.html
index 8f09ac3823..6e5e0661bc 100644
--- a/develop/index.html
+++ b/develop/index.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -264,5 +277,7 @@ Policy</a>. Thank you!</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/jwt.html b/develop/jwt.html
index 8c9cd41a4c..a27b16c90c 100644
--- a/develop/jwt.html
+++ b/develop/jwt.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -281,5 +294,7 @@ print(result.decode(&quot;ascii&quot;))
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/log_contexts.html b/develop/log_contexts.html
index 76f2b55e6a..d753b47300 100644
--- a/develop/log_contexts.html
+++ b/develop/log_contexts.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -481,5 +494,7 @@ lead to leaked logcontexts which are incredibly hard to track down.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/manhole.html b/develop/manhole.html
index a4c0e72968..a01eb526e7 100644
--- a/develop/manhole.html
+++ b/develop/manhole.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -254,5 +267,7 @@ parts of the process.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/media_repository.html b/develop/media_repository.html
index 31670d4b56..dfe9f8037b 100644
--- a/develop/media_repository.html
+++ b/develop/media_repository.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -245,5 +258,7 @@ url_cache_thumbnails/yyyy-mm-dd/aaaaaaaaaaaaaaaa/128-96-image-jpeg-scale
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/message_retention_policies.html b/develop/message_retention_policies.html
index ce9333e698..d22dbfc6d6 100644
--- a/develop/message_retention_policies.html
+++ b/develop/message_retention_policies.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -341,5 +354,7 @@ operating system, the server admin needs to run <code>VACUUM FULL;</code> (or
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/metrics-howto.html b/develop/metrics-howto.html
index ab771f6f4a..282f447552 100644
--- a/develop/metrics-howto.html
+++ b/develop/metrics-howto.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -458,5 +471,7 @@ renamed.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/modules/account_data_callbacks.html b/develop/modules/account_data_callbacks.html
index 9004174bb1..ee8a739a85 100644
--- a/develop/modules/account_data_callbacks.html
+++ b/develop/modules/account_data_callbacks.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -276,5 +289,7 @@ class CustomAccountDataModule:
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/modules/account_validity_callbacks.html b/develop/modules/account_validity_callbacks.html
index de6ed46d89..b16f4b05c4 100644
--- a/develop/modules/account_validity_callbacks.html
+++ b/develop/modules/account_validity_callbacks.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -221,5 +234,7 @@ represented by their Matrix user ID.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/modules/add_extra_fields_to_client_events_unsigned.html b/develop/modules/add_extra_fields_to_client_events_unsigned.html
index b23940d4bd..33109291ed 100644
--- a/develop/modules/add_extra_fields_to_client_events_unsigned.html
+++ b/develop/modules/add_extra_fields_to_client_events_unsigned.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -206,5 +219,7 @@ section, the last-registered callback wins.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/modules/background_update_controller_callbacks.html b/develop/modules/background_update_controller_callbacks.html
index 62851e877b..85a7141aa2 100644
--- a/develop/modules/background_update_controller_callbacks.html
+++ b/develop/modules/background_update_controller_callbacks.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -232,5 +245,7 @@ ensure that progress is always made.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/modules/index.html b/develop/modules/index.html
index d56942176c..19170e84c0 100644
--- a/develop/modules/index.html
+++ b/develop/modules/index.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -227,5 +240,7 @@ another part of Synapse's configuration file.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/modules/password_auth_provider_callbacks.html b/develop/modules/password_auth_provider_callbacks.html
index 941dc90d12..3c4695947b 100644
--- a/develop/modules/password_auth_provider_callbacks.html
+++ b/develop/modules/password_auth_provider_callbacks.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -424,5 +437,7 @@ class MyAuthProvider:
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/modules/porting_legacy_module.html b/develop/modules/porting_legacy_module.html
index b19e5c6612..2e2a84c106 100644
--- a/develop/modules/porting_legacy_module.html
+++ b/develop/modules/porting_legacy_module.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -202,5 +215,7 @@ for more info).</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/modules/presence_router_callbacks.html b/develop/modules/presence_router_callbacks.html
index 1574797c03..ae3965ae0c 100644
--- a/develop/modules/presence_router_callbacks.html
+++ b/develop/modules/presence_router_callbacks.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -273,5 +286,7 @@ class CustomPresenceRouter:
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/modules/spam_checker_callbacks.html b/develop/modules/spam_checker_callbacks.html
index 4b5378feaa..f4ea893a2a 100644
--- a/develop/modules/spam_checker_callbacks.html
+++ b/develop/modules/spam_checker_callbacks.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -564,5 +577,7 @@ class ListSpamChecker:
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/modules/third_party_rules_callbacks.html b/develop/modules/third_party_rules_callbacks.html
index d235c91239..cde8a46439 100644
--- a/develop/modules/third_party_rules_callbacks.html
+++ b/develop/modules/third_party_rules_callbacks.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -433,5 +446,7 @@ class EventCensorer:
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/modules/writing_a_module.html b/develop/modules/writing_a_module.html
index 5c0ac0de25..3dd426b277 100644
--- a/develop/modules/writing_a_module.html
+++ b/develop/modules/writing_a_module.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -294,5 +307,7 @@ class MyModule:
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/openid.html b/develop/openid.html
index b312546436..03f8a39274 100644
--- a/develop/openid.html
+++ b/develop/openid.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -815,5 +828,7 @@ are randomly generated data.</li>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/opentracing.html b/develop/opentracing.html
index b3a11206dd..f502eb3286 100644
--- a/develop/opentracing.html
+++ b/develop/opentracing.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -263,5 +276,7 @@ logged to OpenTracing's logs.</li>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/other/running_synapse_on_single_board_computers.html b/develop/other/running_synapse_on_single_board_computers.html
index aa3a7a3f2d..3cbf69f044 100644
--- a/develop/other/running_synapse_on_single_board_computers.html
+++ b/develop/other/running_synapse_on_single_board_computers.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -235,5 +248,7 @@ admin@homeserver:~$ sudo --user postgres psql matrix-synapse --command 'select c
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/password_auth_providers.html b/develop/password_auth_providers.html
index a95d69b453..49421d6e7c 100644
--- a/develop/password_auth_providers.html
+++ b/develop/password_auth_providers.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -299,5 +312,7 @@ wait for the <code>Awaitable</code> to complete, but the result is ignored.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/postgres.html b/develop/postgres.html
index c45c8502a7..db2a0655d4 100644
--- a/develop/postgres.html
+++ b/develop/postgres.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -394,5 +407,7 @@ successfully.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/print.html b/develop/print.html
index f214cc1be1..b731431958 100644
--- a/develop/print.html
+++ b/develop/print.html
@@ -29,6 +29,7 @@
         <link rel="stylesheet" href="docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -104,6 +105,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -19707,6 +19720,8 @@ admin@homeserver:~$ sudo --user postgres psql matrix-synapse --command 'select c
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="docs/website_files/version.js"></script>
         <script type="text/javascript">
         window.addEventListener('load', function() {
             window.setTimeout(window.print, 100);
diff --git a/develop/replication.html b/develop/replication.html
index 7b8c99e8e4..88e43013f1 100644
--- a/develop/replication.html
+++ b/develop/replication.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -213,5 +226,7 @@ the classes interact, can be found in
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/reverse_proxy.html b/develop/reverse_proxy.html
index 3257ac9ff0..2e575880cc 100644
--- a/develop/reverse_proxy.html
+++ b/develop/reverse_proxy.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -411,5 +424,7 @@ we do not recommend exposing them to the public internet without good reason.</p
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/room_and_user_statistics.html b/develop/room_and_user_statistics.html
index 503403bd18..24c08d37d1 100644
--- a/develop/room_and_user_statistics.html
+++ b/develop/room_and_user_statistics.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -200,5 +213,7 @@ statistics for a room. Each subject can only have one entry.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/server_notices.html b/develop/server_notices.html
index f205f42c25..3280167f0c 100644
--- a/develop/server_notices.html
+++ b/develop/server_notices.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -231,5 +244,7 @@ displayname and avatar of the Server Notices user.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/setup/forward_proxy.html b/develop/setup/forward_proxy.html
index e8c3cddef2..3e1c491c79 100644
--- a/develop/setup/forward_proxy.html
+++ b/develop/setup/forward_proxy.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -260,5 +273,7 @@ your <a href="../usage/configuration/homeserver_sample_config.html">homserver.ya
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/setup/installation.html b/develop/setup/installation.html
index 97503eb6eb..d97430bcac 100644
--- a/develop/setup/installation.html
+++ b/develop/setup/installation.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -614,5 +627,7 @@ failing, e.g.:</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/setup/turn/coturn.html b/develop/setup/turn/coturn.html
index 810b51ee60..64edc34132 100644
--- a/develop/setup/turn/coturn.html
+++ b/develop/setup/turn/coturn.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -347,5 +360,7 @@ IPv6 address that is mapped by NAT to the external IPv6 address.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/setup/turn/eturnal.html b/develop/setup/turn/eturnal.html
index 6a0099f725..328ae6d53c 100644
--- a/develop/setup/turn/eturnal.html
+++ b/develop/setup/turn/eturnal.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -320,5 +333,7 @@ to query how many active sessions exist, to change logging behaviour and so on.<
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/sso_mapping_providers.html b/develop/sso_mapping_providers.html
index 75f7a992ce..c41d27b51f 100644
--- a/develop/sso_mapping_providers.html
+++ b/develop/sso_mapping_providers.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -442,5 +455,7 @@ specified in the config. It is located at
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/structured_logging.html b/develop/structured_logging.html
index 0b7d4e90b9..882b8112ac 100644
--- a/develop/structured_logging.html
+++ b/develop/structured_logging.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -254,5 +267,7 @@ remote endpoint at 10.1.2.3:9999.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/synctl_workers.html b/develop/synctl_workers.html
index b3a5b8683b..b207ac0487 100644
--- a/develop/synctl_workers.html
+++ b/develop/synctl_workers.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -208,5 +221,7 @@ notifications.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/systemd-with-workers/index.html b/develop/systemd-with-workers/index.html
index 5ad0678060..7177bcb764 100644
--- a/develop/systemd-with-workers/index.html
+++ b/develop/systemd-with-workers/index.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -275,5 +288,7 @@ the changes being applied at a glance.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/tcp_replication.html b/develop/tcp_replication.html
index 6c98552617..c7da983bb2 100644
--- a/develop/tcp_replication.html
+++ b/develop/tcp_replication.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -381,5 +394,7 @@ state</li>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/templates.html b/develop/templates.html
index f4844f8d68..de6013c315 100644
--- a/develop/templates.html
+++ b/develop/templates.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -467,5 +480,7 @@ When rendering, this template is given two variables:
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/turn-howto.html b/develop/turn-howto.html
index b8f2983d7e..8c8cc0976b 100644
--- a/develop/turn-howto.html
+++ b/develop/turn-howto.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -342,5 +355,7 @@ entry in the results.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/upgrade.html b/develop/upgrade.html
index 43143ebc5b..6ffbc82733 100644
--- a/develop/upgrade.html
+++ b/develop/upgrade.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -2146,5 +2159,7 @@ in the local HS will automatically rejoin the room.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/usage/administration/admin_api/background_updates.html b/develop/usage/administration/admin_api/background_updates.html
index a67f7d869b..935acbeaa7 100644
--- a/develop/usage/administration/admin_api/background_updates.html
+++ b/develop/usage/administration/admin_api/background_updates.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../../../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../../../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../../../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../../../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -255,5 +268,7 @@ background updates which won't be cancelled once started.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../../../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../../../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../../../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/usage/administration/admin_api/federation.html b/develop/usage/administration/admin_api/federation.html
index de6a55d40d..5925cba414 100644
--- a/develop/usage/administration/admin_api/federation.html
+++ b/develop/usage/administration/admin_api/federation.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../../../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../../../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../../../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../../../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -357,5 +370,7 @@ even if the API already returns the http status 200.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../../../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../../../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../../../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/usage/administration/admin_api/index.html b/develop/usage/administration/admin_api/index.html
index 0e8be5c8b6..1fff66915e 100644
--- a/develop/usage/administration/admin_api/index.html
+++ b/develop/usage/administration/admin_api/index.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../../../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../../../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../../../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../../../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -217,5 +230,7 @@ information from the Admin API.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../../../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../../../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../../../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/usage/administration/admin_api/registration_tokens.html b/develop/usage/administration/admin_api/registration_tokens.html
index e9ac3206ea..1b2718827b 100644
--- a/develop/usage/administration/admin_api/registration_tokens.html
+++ b/develop/usage/administration/admin_api/registration_tokens.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../../../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../../../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../../../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../../../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -424,5 +437,7 @@ the <a href="https://matrix.org/docs/spec/client_server/r0.6.1#api-standards">Ma
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../../../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../../../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../../../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/usage/administration/admin_faq.html b/develop/usage/administration/admin_faq.html
index d98443f665..1eae7f2210 100644
--- a/develop/usage/administration/admin_faq.html
+++ b/develop/usage/administration/admin_faq.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -394,5 +407,7 @@ you see this failure mode so we can help debug it, however.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/usage/administration/database_maintenance_tools.html b/develop/usage/administration/database_maintenance_tools.html
index 4fc7a88391..25e16dd976 100644
--- a/develop/usage/administration/database_maintenance_tools.html
+++ b/develop/usage/administration/database_maintenance_tools.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -197,5 +210,7 @@
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/usage/administration/index.html b/develop/usage/administration/index.html
index b1a6d96192..7689cdbe3f 100644
--- a/develop/usage/administration/index.html
+++ b/develop/usage/administration/index.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -192,5 +205,7 @@
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/usage/administration/monitoring/reporting_homeserver_usage_statistics.html b/develop/usage/administration/monitoring/reporting_homeserver_usage_statistics.html
index 52611e11ef..bf1c7f5f5a 100644
--- a/develop/usage/administration/monitoring/reporting_homeserver_usage_statistics.html
+++ b/develop/usage/administration/monitoring/reporting_homeserver_usage_statistics.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../../../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../../../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../../../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../../../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -254,5 +267,7 @@ consider using one of the following known implementations:</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../../../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../../../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../../../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/usage/administration/monthly_active_users.html b/develop/usage/administration/monthly_active_users.html
index 6b21ea3bf7..62615677e3 100644
--- a/develop/usage/administration/monthly_active_users.html
+++ b/develop/usage/administration/monthly_active_users.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -249,5 +262,7 @@ registered accounts on the homeserver.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/usage/administration/request_log.html b/develop/usage/administration/request_log.html
index 43db860ef4..aefefe4a64 100644
--- a/develop/usage/administration/request_log.html
+++ b/develop/usage/administration/request_log.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -220,5 +233,7 @@ small processing times.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/usage/administration/state_groups.html b/develop/usage/administration/state_groups.html
index 1e035d2bb0..cd348edd2f 100644
--- a/develop/usage/administration/state_groups.html
+++ b/develop/usage/administration/state_groups.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -198,5 +211,7 @@
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/usage/administration/understanding_synapse_through_grafana_graphs.html b/develop/usage/administration/understanding_synapse_through_grafana_graphs.html
index 5e044a0bcc..8e9d136e55 100644
--- a/develop/usage/administration/understanding_synapse_through_grafana_graphs.html
+++ b/develop/usage/administration/understanding_synapse_through_grafana_graphs.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -235,5 +248,7 @@ to make use of multiple CPU cores / multiple machines for your homeserver.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/usage/administration/useful_sql_for_admins.html b/develop/usage/administration/useful_sql_for_admins.html
index c5753465f7..82b16d5849 100644
--- a/develop/usage/administration/useful_sql_for_admins.html
+++ b/develop/usage/administration/useful_sql_for_admins.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -355,5 +368,7 @@ WHERE room_stats_state.room_id = event_json.room_id&quot; | psql -d synapse -h l
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/usage/configuration/config_documentation.html b/develop/usage/configuration/config_documentation.html
index ccb18e12af..1328367c4d 100644
--- a/develop/usage/configuration/config_documentation.html
+++ b/develop/usage/configuration/config_documentation.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -4057,5 +4070,7 @@ Set a size to change the default.</li>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/usage/configuration/homeserver_sample_config.html b/develop/usage/configuration/homeserver_sample_config.html
index b69f0f0ba5..b363da43a8 100644
--- a/develop/usage/configuration/homeserver_sample_config.html
+++ b/develop/usage/configuration/homeserver_sample_config.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -239,5 +252,7 @@ trusted_key_servers:
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/usage/configuration/index.html b/develop/usage/configuration/index.html
index dc23ebb711..5573fdf5ef 100644
--- a/develop/usage/configuration/index.html
+++ b/develop/usage/configuration/index.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -188,5 +201,7 @@ file should have been generated when you <a href="../../setup/installation.html"
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/usage/configuration/logging_sample_config.html b/develop/usage/configuration/logging_sample_config.html
index 958e3a879d..1d8f907bb3 100644
--- a/develop/usage/configuration/logging_sample_config.html
+++ b/develop/usage/configuration/logging_sample_config.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -270,5 +283,7 @@ disable_existing_loggers: false
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/usage/configuration/user_authentication/index.html b/develop/usage/configuration/user_authentication/index.html
index 3349f6e13f..6cc32a8732 100644
--- a/develop/usage/configuration/user_authentication/index.html
+++ b/develop/usage/configuration/user_authentication/index.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../../../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../../../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../../../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../../../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -198,5 +211,7 @@ modules.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../../../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../../../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../../../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/usage/configuration/user_authentication/refresh_tokens.html b/develop/usage/configuration/user_authentication/refresh_tokens.html
index d3e0ec936c..f5ea6b70f9 100644
--- a/develop/usage/configuration/user_authentication/refresh_tokens.html
+++ b/develop/usage/configuration/user_authentication/refresh_tokens.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../../../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../../../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../../../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../../../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -307,5 +320,7 @@ above requirements will still hold.</em></p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../../../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../../../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../../../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/usage/configuration/user_authentication/single_sign_on/cas.html b/develop/usage/configuration/user_authentication/single_sign_on/cas.html
index f39810dba9..96f1802dd4 100644
--- a/develop/usage/configuration/user_authentication/single_sign_on/cas.html
+++ b/develop/usage/configuration/user_authentication/single_sign_on/cas.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../../../../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../../../../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../../../../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../../../../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -191,5 +204,7 @@ sections of the configuration manual for more details.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../../../../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../../../../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../../../../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/usage/configuration/user_authentication/single_sign_on/index.html b/develop/usage/configuration/user_authentication/single_sign_on/index.html
index e4b8d24a55..1d7fad263b 100644
--- a/develop/usage/configuration/user_authentication/single_sign_on/index.html
+++ b/develop/usage/configuration/user_authentication/single_sign_on/index.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../../../../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../../../../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../../../../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../../../../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -189,5 +202,7 @@ auth provider modules.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../../../../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../../../../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../../../../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/usage/configuration/user_authentication/single_sign_on/saml.html b/develop/usage/configuration/user_authentication/single_sign_on/saml.html
index 9365206e05..0a9fe36b15 100644
--- a/develop/usage/configuration/user_authentication/single_sign_on/saml.html
+++ b/develop/usage/configuration/user_authentication/single_sign_on/saml.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="../../../../docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="../../../../docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="../../../../docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="../../../../docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -191,5 +204,7 @@ file</a> for more details.</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="../../../../docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="../../../../docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="../../../../docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/user_directory.html b/develop/user_directory.html
index 512d8d7704..ffbb728855 100644
--- a/develop/user_directory.html
+++ b/develop/user_directory.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -315,5 +328,7 @@ returned first.</li>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/website_files/theme/index.hbs b/develop/website_files/theme/index.hbs
index 3b7a5b6163..f60a7e96aa 100644
--- a/develop/website_files/theme/index.hbs
+++ b/develop/website_files/theme/index.hbs
@@ -131,6 +131,18 @@
                             <i class="fa fa-search"></i>
                         </button>
                         {{/if}}
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">{{ book_title }}</h1>
diff --git a/develop/website_files/version-picker.css b/develop/website_files/version-picker.css
new file mode 100644
index 0000000000..28e5d5219a
--- /dev/null
+++ b/develop/website_files/version-picker.css
@@ -0,0 +1,78 @@
+.version-picker {
+    display: flex;
+    align-items: center;
+}
+
+.version-picker .dropdown {
+    width: 130px;
+    max-height: 29px;
+    margin-left: 10px;
+    display: inline-block;
+    border-radius: 4px;
+    border: 1px solid var(--theme-popup-border);
+    position: relative;
+    font-size: 13px;
+    color: var(--fg);
+    height: 100%;
+    text-align: left;
+}
+.version-picker .dropdown .select {
+    cursor: pointer;
+    display: block;
+    padding: 5px 2px 5px 15px;
+}
+.version-picker .dropdown .select > i {
+    font-size: 10px;
+    color: var(--fg);
+    cursor: pointer;
+    float: right;
+    line-height: 20px !important;
+}
+.version-picker .dropdown:hover {
+    border: 1px solid var(--theme-popup-border);
+}
+.version-picker .dropdown:active {
+    background-color: var(--theme-popup-bg);
+}
+.version-picker .dropdown.active:hover,
+.version-picker .dropdown.active {
+    border: 1px solid var(--theme-popup-border);
+    border-radius: 2px 2px 0 0;
+    background-color: var(--theme-popup-bg);
+}
+.version-picker .dropdown.active .select > i {
+    transform: rotate(-180deg);
+}
+.version-picker .dropdown .dropdown-menu {
+    position: absolute;
+    background-color: var(--theme-popup-bg);
+    width: 100%;
+    left: -1px;
+    right: 1px;
+    margin-top: 1px;
+    border: 1px solid var(--theme-popup-border);
+    border-radius: 0 0 4px 4px;
+    overflow: hidden;
+    display: none;
+    max-height: 300px;
+    overflow-y: auto;
+    z-index: 9;
+}
+.version-picker .dropdown .dropdown-menu li {
+    font-size: 12px;
+    padding: 6px 20px;
+    cursor: pointer;
+} 
+.version-picker .dropdown .dropdown-menu {
+    padding: 0;
+    list-style: none;
+}
+.version-picker .dropdown .dropdown-menu li:hover {
+    background-color: var(--theme-hover);
+}
+.version-picker .dropdown .dropdown-menu li.active::before {
+    display: inline-block;
+    content: "✓";
+    margin-inline-start: -14px;
+    width: 14px;
+}
\ No newline at end of file
diff --git a/develop/website_files/version-picker.js b/develop/website_files/version-picker.js
new file mode 100644
index 0000000000..bb35a7d896
--- /dev/null
+++ b/develop/website_files/version-picker.js
@@ -0,0 +1,127 @@
+
+const dropdown = document.querySelector('.version-picker .dropdown');
+const dropdownMenu = dropdown.querySelector('.dropdown-menu');
+
+fetchVersions(dropdown, dropdownMenu).then(() => {
+    initializeVersionDropdown(dropdown, dropdownMenu);
+});
+
+/**
+ * Initialize the dropdown functionality for version selection.
+ * 
+ * @param {Element} dropdown - The dropdown element.
+ * @param {Element} dropdownMenu - The dropdown menu element.
+ */
+function initializeVersionDropdown(dropdown, dropdownMenu) {
+    // Toggle the dropdown menu on click
+    dropdown.addEventListener('click', function () {
+        this.setAttribute('tabindex', 1);
+        this.classList.toggle('active');
+        dropdownMenu.style.display = (dropdownMenu.style.display === 'block') ? 'none' : 'block';
+    });
+  
+    // Remove the 'active' class and hide the dropdown menu on focusout
+    dropdown.addEventListener('focusout', function () {
+        this.classList.remove('active');
+        dropdownMenu.style.display = 'none';
+    });
+  
+    // Handle item selection within the dropdown menu
+    const dropdownMenuItems = dropdownMenu.querySelectorAll('li');    
+    dropdownMenuItems.forEach(function (item) {
+        item.addEventListener('click', function () {
+            dropdownMenuItems.forEach(function (item) {
+                item.classList.remove('active');
+            });
+            this.classList.add('active');
+            dropdown.querySelector('span').textContent = this.textContent;
+            dropdown.querySelector('input').value = this.getAttribute('id');
+
+            window.location.href = changeVersion(window.location.href, this.textContent);
+        });
+    });
+};
+
+/**
+ * This function fetches the available versions from a GitHub repository
+ * and inserts them into the version picker.
+ * 
+ * @param {Element} dropdown - The dropdown element.
+ * @param {Element} dropdownMenu - The dropdown menu element.
+ * @returns {Promise<Array<string>>} A promise that resolves with an array of available versions.
+ */
+function fetchVersions(dropdown, dropdownMenu) {
+    return new Promise((resolve, reject) => {
+        window.addEventListener("load", () => {
+
+            fetch("https://api.github.com/repos/matrix-org/synapse/git/trees/gh-pages", {
+                cache: "force-cache",
+            }).then(res => 
+                res.json()
+            ).then(resObject => {
+                const excluded = ['dev-docs', 'v1.91.0', 'v1.80.0', 'v1.69.0'];
+                const tree = resObject.tree.filter(item => item.type === "tree" && !excluded.includes(item.path));
+                const versions = tree.map(item => item.path).sort(sortVersions);
+
+                // Create a list of <li> items for versions
+                versions.forEach((version) => {
+                    const li = document.createElement("li");
+                    li.textContent = version;
+                    li.id = version;
+    
+                    if (window.SYNAPSE_VERSION === version) {
+                        li.classList.add('active');
+                        dropdown.querySelector('span').textContent = version;
+                        dropdown.querySelector('input').value = version;
+                    }
+    
+                    dropdownMenu.appendChild(li);
+                });
+
+                resolve(versions);
+
+            }).catch(ex => {
+                console.error("Failed to fetch version data", ex);
+                reject(ex);
+            })
+        });
+    });
+}
+
+/**
+ * Custom sorting function to sort an array of version strings.
+ *
+ * @param {string} a - The first version string to compare.
+ * @param {string} b - The second version string to compare.
+ * @returns {number} - A negative number if a should come before b, a positive number if b should come before a, or 0 if they are equal.
+ */
+function sortVersions(a, b) {
+    // Put 'develop' and 'latest' at the top
+    if (a === 'develop' || a === 'latest') return -1;
+    if (b === 'develop' || b === 'latest') return 1;
+
+    const versionA = (a.match(/v\d+(\.\d+)+/) || [])[0];
+    const versionB = (b.match(/v\d+(\.\d+)+/) || [])[0];
+
+    return versionB.localeCompare(versionA);
+}
+
+/**
+ * Change the version in a URL path.
+ *
+ * @param {string} url - The original URL to be modified.
+ * @param {string} newVersion - The new version to replace the existing version in the URL.
+ * @returns {string} The updated URL with the new version.
+ */
+function changeVersion(url, newVersion) {
+    const parsedURL = new URL(url);
+    const pathSegments = parsedURL.pathname.split('/');
+  
+    // Modify the version
+    pathSegments[2] = newVersion;
+
+    // Reconstruct the URL
+    parsedURL.pathname = pathSegments.join('/');
+  
+    return parsedURL.href;
+}
\ No newline at end of file
diff --git a/develop/website_files/version.js b/develop/website_files/version.js
new file mode 100644
index 0000000000..6279bc07bf
--- /dev/null
+++ b/develop/website_files/version.js
@@ -0,0 +1 @@
+window.SYNAPSE_VERSION = "develop";
diff --git a/develop/welcome_and_overview.html b/develop/welcome_and_overview.html
index 8f09ac3823..6e5e0661bc 100644
--- a/develop/welcome_and_overview.html
+++ b/develop/welcome_and_overview.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -264,5 +277,7 @@ Policy</a>. Thank you!</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file
diff --git a/develop/workers.html b/develop/workers.html
index 5adf877a4f..89df965ac3 100644
--- a/develop/workers.html
+++ b/develop/workers.html
@@ -28,6 +28,7 @@
         <link rel="stylesheet" href="docs/website_files/table-of-contents.css">
         <link rel="stylesheet" href="docs/website_files/remove-nav-buttons.css">
         <link rel="stylesheet" href="docs/website_files/indent-section-headers.css">
+        <link rel="stylesheet" href="docs/website_files/version-picker.css">
     </head>
     <body>
         <!-- Provide site root to javascript -->
@@ -103,6 +104,18 @@
                         <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                             <i class="fa fa-search"></i>
                         </button>
+                        <div class="version-picker">
+                            <div class="dropdown">
+                                <div class="select">
+                                    <span></span>
+                                    <i class="fa fa-chevron-down"></i>
+                                </div>
+                                <input type="hidden" name="version">
+                                <ul class="dropdown-menu">
+                                    <!-- Versions will be added dynamically in version-picker.js -->
+                                </ul>
+                            </div>
+                        </div>
                     </div>
 
                     <h1 class="menu-title">Synapse</h1>
@@ -915,5 +928,7 @@ in systemd service files, but not required for synctl).</p>
 
         <!-- Custom JS scripts -->
         <script type="text/javascript" src="docs/website_files/table-of-contents.js"></script>
+        <script type="text/javascript" src="docs/website_files/version-picker.js"></script>
+        <script type="text/javascript" src="docs/website_files/version.js"></script>
     </body>
 </html>
\ No newline at end of file