After skimming the site and code: Do not use this, just use anki. Anki has a free web version (anki web), and has free-as-in-AGPL desktop apps as well. Maybe one day this software will be comparable to anki, but right now it's missing spaced-repetition (which is the only thing that really makes large decks usable), and practically all the other features of anki.
Wow, that’s an unnecessarily harsh criticism. The OP spent a lot of time coding this up, it’s still in progress, and they should feel proud of it! Anki isn’t for everybody, and maybe this person made a UI that speaks to some people better than others. I count myself among the camp of people who like SRS but dislike Anki.
But I didn't see a single sentence about how this is different from Anki and why? Why do you want to reinvent the wheel when Anki is good enough?