Anki Books is a flashcards/note-taking app inspired by Anki and my vision of wanting to build a collaborative platform for making Anki flashcards, with the twist that the flashcards would be inside online "books" that learners could study before downloading the flashcards. It is free and open source: Anki Books source code

Open user registration for Anki Books will not be possible for the time being, but I made public a few of my "books" that I think are at least decent depending on your interests: