A free, open-source Japanese flashcard app for learning numbers, hiragana, katakana, kanji, and vocabulary.
Website: manabu.ninja Web App: app.manabu.ninja Source Code: fossil.manabu.ninja
✨ Features
Manabu Ninja helps you learn Japanese from scratch through focused repetition. It covers numbers, kana, basic kanji, and vocabulary -- starting simple and building up as you master each card. Everything runs offline with progress saved locally, so you can practice anywhere without an account.
- Five study categories -- Numbers (0-9999), Hiragana, Katakana, Kanji (JLPT N5), Vocabulary
- Four practice modes -- Flashcards (self-assessment), Quiz (multiple choice), Word Builder (text input), Drawing (stroke practice with KanjiVG data)
- Spaced repetition -- 3 consecutive correct answers to master a card; wrong answers reset progress and push the card back
- Gamification -- XP, levels, achievements, daily goals, streak tracking
- Text-to-speech -- Native Japanese TTS for listening practice (gracefully disabled when unavailable)
- Offline-first -- All content bundled in the app; Drift/SQLite database for progress persistence
- Material 3 theming -- Light/dark mode with customizable accent colors
- Android, Windows, and Web supported
📥 Downloads
| Platform | Link |
|---|---|
| Android (APK) | manabu_ninja.apk |
| Windows (EXE) | manabu_ninja.exe |
| Web | app.manabu.ninja |
🚀 Quick Start
fossil clone https://fossil.manabu.ninja manabu-ninja.fossil
mkdir manabu-ninja && cd manabu-ninja
fossil open ../manabu-ninja.fossil
flutter pub get
flutter run
See CONTRIBUTING.md for full development setup, building, and releasing.
🪨 About Fossil
This project uses Fossil instead of Git. Fossil is a single binary that bundles version control, a bug tracker, wiki, forum, and web UI -- no separate hosting platform needed. If you've used Git, the workflow is very similar.
See FOSSIL.md for install instructions, daily workflow, and a Git-to-Fossil cheat sheet.
📖 Other Documentation
- CONTRIBUTING.md -- Prerequisites, dev workflow, building, releasing, code style
- FOSSIL.md -- Fossil version control guide for Git users
- astro/README.md -- Marketing website development
- infra/README.md -- Server infrastructure and deployment
📄 License
MIT License. KanjiVG stroke order data by Ulrich Apel is licensed under CC BY-SA 3.0.
Klutch Software Inc.