# Words on Repeat

> A spaced repetition vocabulary learning app powered by the FSRS algorithm.

Words on Repeat is a web-based flashcard application for language learners. It uses the FSRS (Free Spaced Repetition Scheduler) algorithm — the most accurate open-source spaced repetition scheduler available — to schedule vocabulary reviews at the optimal moment for long-term retention.

## Key Features

- FSRS spaced repetition algorithm (peer-reviewed, 20-30% more efficient than SM-2/Anki)
- Multi-deck vocabulary management with source/target language configuration
- 4-grade review system: Again, Hard, Good, Easy
- Learning analytics: retention rate, daily reviews, due forecast, study time tracking
- Import from AI assistants (Claude, ChatGPT) via paste JSON or REST API
- Deck sharing between users (read-only)
- JSON import/export with FSRS state preservation
- REST API with 30+ endpoints and API key authentication
- Works on any device (responsive web app, no install needed)

## Who It's For

Language learners who want an efficient, science-backed vocabulary tool. Particularly useful for learners who want to:
- Build vocabulary using spaced repetition without the complexity of Anki
- Generate vocabulary words with AI assistants and import them directly
- Track their learning progress with detailed analytics
- Self-host their vocabulary data

## How It Works

1. Create a deck for your target language (e.g., Spanish to English)
2. Add vocabulary words manually, import JSON, or use AI to generate words
3. Review due cards daily — FSRS schedules each word at the optimal moment
4. Track retention rate, study time, and progress over time

## Technical Details

- Stack: Node.js, Express, SQLite, vanilla JavaScript frontend
- Algorithm: FSRS v7 (ts-fsrs library), 3-variable DSR memory model
- Auth: JWT cookies + API key (Bearer token) authentication
- Open source: https://github.com/piotrpalach86/vocab-app

## Links

- Website: https://wordsonrepeat.com
- Guide/Documentation: https://wordsonrepeat.com/guide
- API Spec (machine-readable): https://wordsonrepeat.com/api/spec
- GitHub: https://github.com/piotrpalach86/vocab-app

## API Access

The REST API supports programmatic vocabulary management. Generate an API key in Settings, then use `Authorization: Bearer sk_...` header. Key endpoints:
- GET /api/decks — list decks
- GET /api/vocabulary?deck_id=N — list words
- POST /api/vocabulary/batch — batch import words
- GET /api/spec — full API specification (no auth required)