It is a small flashcard app that runs in this page. You write cards with a question on the front and the answer on the back, study them one at a time with a flip, and say whether you knew the answer. A spaced-repetition schedule then decides when each card comes back: cards you keep getting right appear less and less often, cards you miss come back the next day. You can keep several decks (vocabulary, formulas, dates, anatomy), search and edit cards, and move them in and out as CSV or JSON.
Your decks are saved in this browser's local storage and nowhere else. Nothing is uploaded, there is no account, and clearing the site data or using a private window removes them, so export a JSON backup now and then.
How to use it
- Pick or create a deck at the top. The deck name field renames it.
- On Cards, type a front and a back and press Add card (Ctrl+Enter in the back field also adds). Multi-line text is kept.
- On Study, press Start studying. Read the question, try to answer in your head, then Show answer (or press Space or Enter).
- Press Knew it (key 2) or Didn't know (key 1). Each button shows where the card goes and when it returns.
- When the queue is empty you see how many you knew and the date of the next review. Practise all cards runs through the whole deck without touching the schedule, useful the night before an exam.
To bring cards in, go to Import and export: paste two columns copied from a spreadsheet, or open a CSV, TSV or JSON file. The first column becomes the front and the second the back; a header row such as front,back, term,definition or question,answer is recognised and skipped.
The schedule: five Leitner boxes
The tool uses the Leitner system with fixed, doubling intervals:
| Box | Next review after |
|---|
| 1 | 1 day |
|---|
| 2 | 2 days |
|---|
| 3 | 4 days |
|---|
| 4 | 8 days |
|---|
| 5 | 16 days |
|---|
A new card sits in box 1 and is due at once. Knew it moves the card up one box and schedules it after that box's interval; a card in box 5 stays there and returns every 16 days. Didn't know sends it back to box 1, due tomorrow. Intervals count from the day you actually review, so studying a few days late is fine.
A worked example: a card first studied on Wednesday 14 October 2026 and answered correctly goes to box 2 and is due on 16 October. Right again: box 3, due 20 October. Missed on the 20th: box 1, due 21 October. Then right four times in a row: 23 October (box 2), 27 October (box 3), 4 November (box 4) and 20 November (box 5). A missed card also comes back once more at the end of the same session, for practice only, so you leave having seen the correct answer.
The full reasoning, with a review calendar, is in how spaced repetition schedules your reviews.
CSV export has a front,back header and follows RFC 4180: fields with commas, quotes or line breaks are quoted, quotes are doubled. Spreadsheets, Anki's text import and Quizlet's import read it. JSON export keeps each card's box, due date and counts, so it restores your progress exactly; use JSON (all decks) as a backup. Imported JSON is checked field by field and a file from another program is refused with a message rather than half-loaded. To clean up a word list before importing, the text toolkit can sort lines and remove duplicates, and the CSV and JSON converter checks a file's columns.
Tips for cards that work
Keep one fact per card: "capital of Laos" beats "capitals of Laos, Cambodia and Myanmar". Write the front as a question you could answer in a few seconds. Add both directions as separate cards when both matter (word to meaning and meaning to word). Be honest with Knew it: a half-remembered answer is a miss, and the box system only works if the hard cards come back. Fifteen focused minutes a day, for example timed with the Pomodoro timer, does more than one long session a week.
