I'm pretty sure the go to is Anki - http://ankisrs.net/ http://ankisrs.net/ which is based on Spaced Repetition - https://en.wikipedia.org/wiki/Spaced_repetitio

I'm pretty sure the go to is Anki - http://ankisrs.net/ http://ankisrs.net/ which is based on Spaced Repetition - https://en.wikipedia.org/wiki/Spaced_repetition https://en.wikipedia.org/wiki/Spaced_repetition