[dan-g]

Since Anki has been coming up quite a bit in the comments, and this is a self-hostable (but not yet spaced repetition) flashcard system, I wanted to note that Anki does let you run your own sync server now: https://docs.ankiweb.net/sync-server.html

[dan-g]

Not quite sure why this deserves a downvote, it’s pertinent since it’s also an open-source flashcard system and there are lots of other comments about it, but okay!