This looks like it's going to be a great application!

Having used many SRS systems over the years, one of the features I wish more had was the ability to remove what I call "mastered" cards from each deck. This would be helpful with stopping the SRS algorithm from continuously feeding old cards.

Another feature that should be integrated into any new SRS is automatic checking from the app to see if the user has been in active for a period of time.

This period would preferably be set by the user themselves, but what it prevents is the inevitable SRS card backlog nightmare, that eventually drives many users to stop using the SRS.

It's happened to just recently for me with Japanese. I went on a vacation didn't study, then I load up my SRS and see over 600 cards in the queue. While some might not mind the challenge of slowly chipping away at the number, many won't invest the time to clear the backlog, I know I haven't. This is especially true if you want to continue learning new words, because that only compounds that backlog.

Normal options in this scenario are to slowly complete the reviews. Or wipe the SRS and start again. Both are bitter pills to swallow.

If Kaards implements a "pause SRS" feature or a way to remove "mastered" cards from the deck (perhaps, there could be a mastered button among the standard SRS proficiency rating buttons) I think that would help make it definitely standout from most SRS services right now.