Zorbi - Spaced-Repetition Flashcards - Other tools are built by boomers, Zorbi is built by students.
Mochi - Write notes and flashcards with Markdown and study them with spaced repetition.
Yak Tack - remember. words.
Anki - Anki is a program which makes remembering things easy. Because it's a lot more efficient than traditional study methods, you can either greatly decrease your time spent studying, or greatly increase the amount you learn.
CleverDeck - Learn languages more efficiently with spaced repetition
ArticleWise - Turn any article into a flash card, in seconds 💡📝