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Spaced repetition for anything you study

A study partner that remembers for you.

Add what you’re learning — words, formulas, concepts, problems. Each card comes back on the day you’re about to forget it, then again 3, 7, 14, 30 and 60 days later, until it sticks.

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The demo needs no account. It runs on sample cards, entirely in your browser.

The Review Queue: today’s due cards across DSA, System Design and AWS, with a progress ring and a streak

How it works

  1. 1

    Add a card

    Something you want to remember, with its answer: a word, a formula, a concept, a problem you solved.

  2. 2

    Review it tomorrow

    Reveal the answer, then grade yourself honestly: Got it, or Struggled.

  3. 3

    Watch the gaps grow

    Each “Got it” pushes the next review further out (1, 3, 7, 14, 30, then 60 days); a struggle brings it back sooner.

Active recall, not rereading

The answer stays hidden until you’ve tried. Reveal it, then grade yourself — and the card is rescheduled on the spot. Timed problems log how long you took.

A review session: a System Design question with its answer revealed and Got it / Struggled buttons

See what’s actually sticking

Recall rate, a study heatmap, how each deck is progressing, and the cards that keep slipping.

The Stats page: recall rate, due count, retained cards, an activity heatmap and the proficiency split

Under the hood

For the engineers reading: what makes it work.

  • Local-first, works offline

    Every screen reads from an in-browser store kept in IndexedDB, so it opens instantly and keeps working without a connection. Installable as a PWA.

  • An offline queue that can’t double-count

    Reviews made offline queue up and replay later. Each carries an idempotency key, so a retried send is recognised instead of counted twice.

  • A schedule derived from history

    A card’s level is replayed from its full attempt history, and each review and its new level commit in one database transaction.

  • Next.js 16 and Turso

    React 19 on the App Router, libSQL/Turso on the server, deployed on AWS Lambda and CloudFront.

  • Tested

    Hundreds of Vitest unit tests, including the scheduler, the sync queue and the routing rules, plus Playwright end-to-end tests.

  • A demo that touches nothing

    The demo runs the real app on generated sample data in its own browser database. Nothing it does can reach a server.

Read the code on GitHub

See it with real-looking data

Three months of reviews across 40 sample cards — due today, overdue, struggling and mastered.

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