synapse/docs/administration/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.

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

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"
}

Response:

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