MatrixSynapse/docs/admin_api/room_membership.md

Edit Room Membership API

This API allows an administrator to join an user account with a given user_id to a room with a given room_id_or_alias. You can only modify the membership of local users. The server administrator must be in the room and have permission to invite users.

Parameters

The following parameters are available:

• user_id - Fully qualified user: for example, @user:server.com.
• room_id_or_alias - The room identifier or alias to join: for example, !636q39766251:server.com.

Usage

POST /_synapse/admin/v1/join/<room_id_or_alias>

{
  "user_id": "@user:server.com"
}

To use it, you will need to authenticate by providing an access_token for a server admin: see Admin API.

Response:

{
  "room_id": "!636q39766251:server.com"
}