Leitner Box Tracker

The Leitner system uses discrete boxes with fixed intervals (1, 2, 4, 8, 16 days), making it predictable and easy to manage. Other methods like SM-2 adjust intervals dynamically based on how difficult each card feels. Both work well—Leitner is simpler to implement and understand, while SM-2 may optimize interval lengths more precisely over time.

A card is due today if today's date is on or after its last review date plus its box interval. For example, a Box 2 card reviewed on Monday is due on Wednesday (2 days later). Unreviewed cards are always due immediately. The system uses your device's local date; no network sync is needed.

The card advances to the next box (Box 1→2, Box 2→3, etc.), capped at Box 5. Its last-reviewed date updates to today. The longer interval of the new box means it won't be due again until later.

The card resets immediately to Box 1, regardless of which box it was in. Its last-reviewed date updates to today, so it will be due again tomorrow (Box 1 reviews daily). This reinforces difficult concepts with frequent practice.

Yes. Your entire deck is stored in your browser's local storage under the key learn.leitner.deck. As long as you don't clear your browser cache, your cards and review history persist. The data never leaves your device—there is no server or account needed.

Yes. Each card has a delete button. Deleted cards are removed permanently from your deck (but remain in your browser history if you want to recover them manually via developer tools).