I launched https://rebrain.gg/ a few days ago.

It's a bit like Reddit but focused on learning. (Doom learning instead of doom scrolling)

You 1) upload a source 2) direct the kind of questions you want to be asked 3) start answering (and if you get the answers wrong, you can discuss the problem with "AI").

You can read other people's sources, questions, answers and their discussions with AI too.

And if you're learning the same thing as other people, you can join communities to share sources/questions.

It's still very early on, so I'm very interested in any feedback.