Cards makes study decks and drills you on them with spaced repetition — the ones you get wrong come back sooner (a Leitner-box system). Decks are saved in this browser on this device; export a deck to move it or back it up. Nothing is uploaded.

Deck

Front (question)	Back (answer)

Spaced repetition here uses five Leitner boxes: a correct answer promotes a card to a longer interval, a miss sends it back to box 1. Progress and decks live in this browser's storage — clearing site data or using another device won't carry them over, so export anything you want to keep. Everything runs on your device.