Free, open-source mini-tools for freelancers and small businesses in Germany.
Invoicing, e-invoices, tax letters, and tax estimates — no sign-up, no watermarks, 100% free.
Every tool in this repo is a fully standalone Next.js mini-app: copy one folder anywhere, npm install && npm run dev, done. Use them live on norman.finance or self-host your own copy.
| Tool | What it does | Live | Source |
|---|---|---|---|
| Tax Calculator | Estimate German income tax, solidarity surcharge, and health insurance for the self-employed — fully client-side | norman.finance | apps/tax-calculator |
| E-Invoice Generator | Create compliant ZUGFeRD PDF e-invoices with live totals and VAT logic (§19, reverse charge) | norman.finance | apps/e-invoice-generator |
| Tax Letter Assistant | AI that explains Finanzamt letters in plain language — urgency, deadlines, required actions | norman.finance | apps/tax-letter-assistant |
| Invoice Generator | Classic invoice maker with a live preview and PDF output | self-host | apps/invoice-generator |
| Steuer-Check | Tax-deduction finder companion — scans bank statements for missed deductions via a custom GPT | self-host | apps/steuer-check |
git clone https://github.com/norman-finance/norman-tools.git
cd norman-tools/apps/tax-calculator # or any other tool
npm install # pnpm works too
npm run devEach app folder is self-contained — no workspace dependencies, no shared packages. You can copy a single apps/<tool> folder out of this repo and it still builds and runs.
To work on all tools at once, use pnpm from the repo root:
pnpm install
pnpm build # builds every app
pnpm dev:tax-calculator # or dev:e-invoice-generator, dev:tax-letter-assistant, ...🧮 Tax Calculator — apps/tax-calculator
Estimate your yearly German taxes as a freelancer or solo self-employed: income tax (Einkommensteuer), solidarity surcharge (Solidaritätszuschlag), and statutory health + care insurance — with marital status and children factored in.
- 100% client-side: no backend, no data leaves the browser
- German 2024 tax brackets with single/married splitting
- Statutory health insurance (14% + Zusatzbeitrag) and care insurance with child discounts
- Languages: Deutsch, English, Русский
Environment: none.
🧾 E-Invoice Generator — apps/e-invoice-generator
Create German-compliant e-invoices with a live preview: client and company details, VAT handling (Kleinunternehmer §19 UStG, EU reverse charge, §3a), 18 currencies, and ZUGFeRD PDF output.
- Live invoice preview and totals while you type
- Smart VAT recommendations based on client country and sale type
- Invoice PDF language: German or English; UI also in Russian
- PDF/ZUGFeRD generation happens via Norman's free public API (
api.norman.finance) — no key required
Environment:
| Variable | Required | Description |
|---|---|---|
NEXT_PUBLIC_INVOICE_API_URL |
no | Override the generation endpoint (default: https://api.norman.finance) |
✉️ Tax Letter Assistant — apps/tax-letter-assistant
Upload a letter from the German tax office (PDF, JPG, or PNG) and get a plain-language summary: what it says, how urgent it is, the deadline, and what to do next — with follow-up questions.
- PDFs are parsed client-side (PDF.js); only extracted text is sent to the API
- Personal data (names, addresses, tax IDs, IBANs) is redacted before any AI call
- Explicit AI-consent checkbox, enforced server-side
- Rate limiting per IP + global daily budget (in-memory, or Upstash Redis if configured)
Environment:
| Variable | Required | Description |
|---|---|---|
OPENAI_API_KEY |
yes | OpenAI key used by the analysis route (gpt-4.1) |
UPSTASH_REDIS_REST_URL |
no | Upstash Redis for cross-instance rate limiting |
UPSTASH_REDIS_REST_TOKEN |
no | — |
📄 Invoice Generator — apps/invoice-generator
The classic Norman invoice maker: a full invoice form with a live side-by-side preview, German + English invoice output, and professional PDF download.
- Live preview updates as you type
- VAT logic incl. Kleinunternehmer and EU reverse charge
- URL-shareable state (
?ui_lang=de) - PDF generation via Norman's free public API — no key required
Environment:
| Variable | Required | Description |
|---|---|---|
NEXT_PUBLIC_API_URL |
no | Override the generation endpoint (default: https://api.norman.finance) |
🔎 Steuer-Check — apps/steuer-check
A companion page for the Steuer-Spar-Scout custom GPT: upload a bank statement export and let AI scan every transaction for missed deductions — home office, travel, tech, insurance, and more.
- Static page, no backend and no keys
- Links out to the free custom GPT (ChatGPT account required there)
- Languages: Deutsch, English
Environment: none.
norman-tools/
├── apps/
│ ├── tax-calculator/ # client-side German income-tax calculator
│ ├── e-invoice-generator/ # ZUGFeRD e-invoice generator (public API)
│ ├── tax-letter-assistant/ # AI Finanzamt-letter explainer (OpenAI)
│ ├── invoice-generator/ # classic invoice maker with live preview
│ └── steuer-check/ # tax-deduction finder companion (GPT)
├── assets/ # screenshots + logo for this README
└── .github/workflows/ # CI: builds every app + standalone check
Every app ships its own package.json, README.md, and (where relevant) .env.example and Dockerfile.
Each app builds to a standalone Next.js server:
cd apps/tax-letter-assistant
npm install && npm run build
OPENAI_API_KEY=sk-... npm startApps with a Dockerfile can be containerized directly — secrets are runtime-only, never baked into the image:
docker build -t tax-letter-assistant apps/tax-letter-assistant
docker run -p 3000:3000 -e OPENAI_API_KEY=sk-... tax-letter-assistantIssues and PRs are welcome — from copy fixes to new tools. If you build something useful for freelancers in Germany on top of these apps, we'd love to hear about it.
Found a bug or have a tool idea? Open an issue →
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