Free flashcard scheduler using the Leitner spaced-repetition system. See when to review each card box.
The Leitner system organizes flashcards into boxes reviewed at increasing intervals. Cards you answer correctly move up a box (longer interval); cards you miss drop back to box 1 (daily review). This spaced-repetition approach concentrates your effort on what you're about to forget, making memorization dramatically more efficient than mass review.