Syncthing can save revisions, and is open source -- I remember now https://docs.syncthing.net/users/versioning.html https://docs.syncthing.net/users/versioning

Syncthing can save revisions, and is open source -- I remember now https://docs.syncthing.net/users/versioning.html https://docs.syncthing.net/users/versioning.html Lots of config options