🦀 OpenKani

Self-hosted WaniKani backend. Own your data, zero API calls after migration.

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Migrate your WaniKani progress once → all data lives in your own Turso SQLite databases → every request stays on your infra. Works with forked clients on web, iOS, and Android.

Runs entirely on free tiers — Vercel Hobby + Turso Starter. No credit card needed.

Try it now

No deploy needed — use the public instance to test:

	URL
API	openkani.vercel.app
Web client	kanji-school.vercel.app

Go to kanji-school.vercel.app, enter your WaniKani API key, and start using it immediately. Deploy your own instance later if you want full control.

Why OpenKani?

There is no other open-source, self-hosted WaniKani backend with API v2 compatibility. Here's how alternatives compare:

	OpenKani	WaniKani	Anki	Kanji Koohii	KaniWani
Self-hosted	✅	❌	✅ (sync server)	✅	❌
WK API v2 compatible	✅	✅ (source)	❌	❌	Partial
Structured kanji curriculum	✅	✅	❌	RTK only	❌ (reverse only)
SRS built-in	✅	✅	✅	✅	✅
Per-user isolated DB	✅	❌	❌	❌	❌
Mobile clients	✅	✅	✅	❌	❌
Free forever	✅	❌ ($9/mo)	✅	✅	✅
Migrate existing progress	✅	—	❌	❌	❌

Key differentiators:

• One-time migration — import all WK data, never call their API again
• Per-user SQLite — each user gets an isolated Turso database, not shared tables
• Drop-in clients — forked KanjiSchool (web), Tsurukame (iOS), Smouldering Durtles (Android) point at your backend
• Free deployment — Vercel free tier + Turso free tier (100 DBs, 9GB storage)

How it works

sequenceDiagram
    participant C as Client
    participant B as OpenKani API
    participant W as WaniKani API
    participant T as Turso

    C->>B: POST /v2/migrate {api_key}
    B->>W: Fetch all user data
    W-->>B: subjects, assignments, reviews...
    B->>T: Create per-user DB (seeded from template)
    B->>T: Bulk insert all data
    B-->>C: {token, counts}

    Note over C,W: After migration — WaniKani API never called again

    C->>B: GET /v2/subjects (Bearer token)
    B->>T: Query user's DB
    T-->>B: Results
    B-->>C: WK API v2 format response

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Quick start

Prerequisites: Bun >= 1.0, Turso CLI

# 1. Setup Turso (one-time)
turso auth api-tokens mint openkani          # platform API token
turso group create openkani                  # DB group
turso group tokens create openkani           # group auth token
turso db create wani-template --group openkani
turso db create wani-registry --group openkani

# 2. Clone & configure
git clone https://github.com/sarmientoF/OpenKani.git
cd OpenKani
bun install
cp .env.example .env                         # fill in Turso creds

# 3. Push schemas & run
bun run db:push:template
bun run db:push:registry
bun run dev                                  # http://localhost:3000

Full setup details in docs/SETUP.md

Deploy to Vercel

API

Web client

Set VITE_API_URL to your deployed API URL (e.g. https://openkani.vercel.app).

Both run on Vercel's free Hobby plan. See docs/SETUP.md for env var details.

Clients

App	Platform	Submodule
KanjiSchool	Web (React)	apps/kanji-school
Tsurukame	iOS (Swift)	apps/tsurukame
Smouldering Durtles	Android (Java)	apps/smouldering_durtles

git submodule update --init --recursive

Stack

Backend: Bun · Hono · Drizzle ORM · Turso (per-user libSQL) · Zod Web: React 18 · Vite · Redux Toolkit · Ant Design · Dexie (IndexedDB) Hosting: Vercel (Node.js via @vercel/hono)

Roadmap

• Web client (KanjiSchool)
• iOS client release (Tsurukame fork)
• Android client release (Smouldering Durtles fork)
• Open Claw plugin support

Docs

• Setup & Deployment — full env var reference, Turso setup, Vercel config
• API Reference — all endpoints, request/response formats
• Architecture — per-user DB pattern, schema design, migration flow
• Contributing — dev setup, PR guidelines

License

MIT