freiburg.social is one of the many independent Mastodon servers you can use to participate in the fediverse.
Ein Mastodon-Server für Freiburg und Umland betrieben durch den Verein freiburg.social e.V.: https://wir.freiburg.social

Server stats:

533
active users

Fun D-Ticket quirk: None of the ferries on the bodensee are included, however! There are busses that use the ferry and those are included. And you can just get out of the bus on the ship.