I’ve heard of these (thanks, HN community!) and currently use Anki (for years the Android, Windows, and Linux versions, and recently paid for the iOS version).

I’ve heard of these (thanks, HN community!) and currently use Anki (for years the Android, Windows, and Linux versions, and recently paid for the iOS version). I mostly use cloze deletion to make multiple cards from one. Low barrier to making cards and reinforcing learning. Making effective cards is a work in practice. I start with small chunks to not hit walls.