I made a flashcard site with spaced repetition for learning Japanese (I moved to Japan few years ago). I love the idea behind Anki, but both the interface and having to take decision while trying to memorize were a drag on me, so I made the flashcards for a simple "did I know it or not?".

I attribute around half of the Japanese I still know to repeating cards incessantly one after another for months, few years ago:

https://core.cards/