[marcusbuffett]

I used this for spaced repetition for opening training on Chessbook, can vouch that the Rust package is excellent. Easy to use and immediately lowered the training load on our users while keeping retention high. FSRS is awesome.

[Oreb]

I use Chessbook and mostly like it, but I wish there was a way to configure the spaced repetition parameters. In particular, I find the frequency of reviews too low to retain well, especially for recently added moves.