diff --git a/docs/modules/account_data_callbacks.md b/docs/modules/account_data_callbacks.md
new file mode 100644
index 0000000000..25de911627
--- /dev/null
+++ b/docs/modules/account_data_callbacks.md
@@ -0,0 +1,106 @@
+# Account data callbacks
+
+Account data callbacks allow module developers to react to changes of the account data
+of local users. Account data callbacks can be registered using the module API's
+`register_account_data_callbacks` method.
+
+## Callbacks
+
+The available account data callbacks are:
+
+### `on_account_data_updated`
+
+_First introduced in Synapse v1.57.0_
+
+```python
+async def on_account_data_updated(
+ user_id: str,
+ room_id: Optional[str],
+ account_data_type: str,
+ content: "synapse.module_api.JsonDict",
+) -> None:
+```
+
+Called after user's account data has been updated. The module is given the
+Matrix ID of the user whose account data is changing, the room ID the data is associated
+with, the type associated with the change, as well as the new content. If the account
+data is not associated with a specific room, then the room ID is `None`.
+
+This callback is triggered when new account data is added or when the data associated with
+a given type (and optionally room) changes. This includes deletion, since in Matrix,
+deleting account data consists of replacing the data associated with a given type
+(and optionally room) with an empty dictionary (`{}`).
+
+Note that this doesn't trigger when changing the tags associated with a room, as these are
+processed separately by Synapse.
+
+If multiple modules implement this callback, Synapse runs them all in order.
+
+## Example
+
+The example below is a module that implements the `on_account_data_updated` callback, and
+sends an event to an audit room when a user changes their account data.
+
+```python
+import json
+import attr
+from typing import Any, Dict, Optional
+
+from synapse.module_api import JsonDict, ModuleApi
+from synapse.module_api.errors import ConfigError
+
+
+@attr.s(auto_attribs=True)
+class CustomAccountDataConfig:
+ audit_room: str
+ sender: str
+
+
+class CustomAccountDataModule:
+ def __init__(self, config: CustomAccountDataConfig, api: ModuleApi):
+ self.api = api
+ self.config = config
+
+ self.api.register_account_data_callbacks(
+ on_account_data_updated=self.log_new_account_data,
+ )
+
+ @staticmethod
+ def parse_config(config: Dict[str, Any]) -> CustomAccountDataConfig:
+ def check_in_config(param: str):
+ if param not in config:
+ raise ConfigError(f"'{param}' is required")
+
+ check_in_config("audit_room")
+ check_in_config("sender")
+
+ return CustomAccountDataConfig(
+ audit_room=config["audit_room"],
+ sender=config["sender"],
+ )
+
+ async def log_new_account_data(
+ self,
+ user_id: str,
+ room_id: Optional[str],
+ account_data_type: str,
+ content: JsonDict,
+ ) -> None:
+ content_raw = json.dumps(content)
+ msg_content = f"{user_id} has changed their account data for type {account_data_type} to: {content_raw}"
+
+ if room_id is not None:
+ msg_content += f" (in room {room_id})"
+
+ await self.api.create_and_send_event_into_room(
+ {
+ "room_id": self.config.audit_room,
+ "sender": self.config.sender,
+ "type": "m.room.message",
+ "content": {
+ "msgtype": "m.text",
+ "body": msg_content
+ }
+ }
+ )
+```
diff --git a/docs/modules/writing_a_module.md b/docs/modules/writing_a_module.md
index e7c0ffad58..e6303b739e 100644
--- a/docs/modules/writing_a_module.md
+++ b/docs/modules/writing_a_module.md
@@ -33,7 +33,7 @@ A module can implement the following static method:
```python
@staticmethod
-def parse_config(config: dict) -> dict
+def parse_config(config: dict) -> Any
```
This method is given a dictionary resulting from parsing the YAML configuration for the
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