Fritz

I made Fritz to help my sister learn German for school.

• Vocabulary, grammar, listening, conversations and reading in one place.
• Czech and English instructions; an A1–C1 course.
• 5, 10 or 20-minute lessons based on reviews, recent mistakes and course progress.
• Your own words, test practice, short stories and language mysteries.
• Optional streaks and XP.

Fritz.mov

Get started

Mac

• Requires macOS 14 or later.
• Download Fritz 0.2.0 for Apple Silicon or Intel.
• Unzip the download and move Fritz.app to Applications.
• The packaged app includes its runtime and needs no login setup.
• Builds aren't notarized. On first launch, macOS may require System Settings → Privacy & Security → Open Anyway.
• See release notes or build from source.

Web

Each instance has one learner profile. Install Git and Docker Compose, then run:

git clone https://github.com/Aletheie/Fritz.git
cd Fritz
cp -n .env.docker.example .env
docker compose up --build -d
docker compose exec app node scripts/access-link.mjs

The default address is http://localhost:3000.

1. Open the private link within ten minutes.
2. Create a passkey.
3. Save the recovery code.

For a phone or another computer, configure HTTPS before creating your passkey:

1. Set ORIGIN in .env to a permanent HTTPS address.
2. Put an HTTPS reverse proxy in front of 127.0.0.1:3000.
3. Keep /api/* uncached. Fritz sends HSTS over HTTPS; serve the domain only over HTTPS from then on.
4. Apply changes with docker compose up -d.

You can then install Fritz from your browser's menu.

Your data and access

• Progress stays on this Mac or in this browser. Signing in on another device doesn't sync it.
• Use encrypted backups in Settings to save or move your progress.
• Export before clearing browser data or changing the app's address.
• Keep the backup passphrase somewhere safe.
• Core study works offline after an initial online load.
• Login and AI tools need a connection, including demo responses and the daily conversation step.

Manage passkeys in Settings → Personal access. Existing password accounts can switch to passkeys there.

If you lose access, use the recovery code on the login screen. You can also create a recovery link on your server:

docker compose exec app node scripts/access-link.mjs --recover

Use this after changing domains, too. It keeps your profile identity and AI connection. Don't delete auth.json to reset access.

• Back up the server volume before updating. Older releases can't read the new profile format.
• After pulling updates, run docker compose up --build -d.
• docker compose down keeps your profile. Adding -v deletes its volume.

Optional AI

The course works without an API key. AI tools use demo responses by default.

For live AI feedback:

1. Open Settings → AI.
2. Choose Gemini, Claude or an OpenAI-compatible provider.
3. Enter your API key and model.

• The connection works across your signed-in devices.
• The key stays encrypted in the installation. Learning backups don't include it.
• Selected learning content goes to your provider. API usage is billed separately.
• Disconnect in Settings to remove the connection for all devices.

For local models:

• Enable Ollama or LM Studio with AI_ALLOW_LOCAL_PROVIDERS=true.
• The Mac app enables local models by default.
• In Docker, loopback means the container.
• See .env.docker.example for other server options.

Development

Fritz uses SvelteKit, TypeScript, Tailwind, IndexedDB and ts-fsrs. Use Node.js 22.23.2 (.nvmrc) and pnpm 11.20.0:

git clone https://github.com/Aletheie/Fritz.git
cd Fritz
npm install --global pnpm@11.20.0
pnpm install --frozen-lockfile
cp -n .env.example .env
pnpm dev

• In another terminal, run pnpm access:link from the project folder.
• Open the link, create a passkey and save the recovery code.
• Keep ORIGIN in .env aligned with the local server. The default is http://localhost:5173.

Useful commands:

• Production build: pnpm build.
• Full checks: pnpm quality. First install Chromium with pnpm exec playwright install chromium.
• Benchmarks: see the performance guide.

To package the Mac app, use a Mac with Xcode command-line tools installed:

pnpm build
pnpm release:macos --keep-app

• Find the ZIP and unpacked Fritz.app in artifacts/release/.
• The build targets your Mac's architecture by default.
• Add --arch x64 for Intel or --arch arm64 for Apple Silicon.
• Move the app to Applications before using it.

Content and translations are still being reviewed. Report broken exercises or awkward German in an issue.

MIT license. Reading selections and fonts retain their own credits and licences.