curl -sS -X POST 'https://matrix.example.com/_matrix/client/v3/join/!abc123:example.com' -H "Authorization: Bearer $ACCESS_TOKEN"
Join a room as the logged-in user
Adds the authenticated user to the room, which must be publicly joinable or have invited them first. Accepts a room alias like #dev:example.com as well as a room ID, though aliases need URL encoding. The admin join endpoint can add any local user regardless of join rules. Returns the room ID on success.
Looking for more? Search all 7,657 commands — works offline, in English or Spanish, and fixes typos.