# niehu.es

> Personal portfolio of Stefan Niehues, a solo developer based in Oldenburg, Germany. He builds SaaS tools, websites, and content platforms.

## About

Stefan Niehues is an independent software developer and sole proprietor. He designs, builds, and operates digital products end-to-end — from concept and development to marketing and infrastructure. His stack is primarily Node.js, MySQL, Prisma, and vanilla HTML/CSS/JS.

## Projects

### Own Products

- [Briefmatic](https://briefmatic.de): SaaS tool that generates automated shipping labels for Etsy sellers in Germany. Built with Node.js, Express, Prisma, MySQL, Stripe, and the Etsy API.
- [KartenMockup](https://kartenmockup.de): Browser-based tool for creating greeting card mockups. No signup required.
- [BuchScore](https://buchscore.de): Listing analysis and scoring tool for German-speaking self-publishers on Amazon. Combines rule-based checks with LLM-powered analysis (Claude API + Claude Vision) to score listings 0–100 across blurb, cover, title, keywords, price, and social proof. Freemium model with Stripe.
- [Descrito](https://descrito.de): AI-powered product description generator for Etsy, Vinted, and Kleinanzeigen sellers in the DACH region. Uses Anthropic's Haiku API with a deterministic fallback system for character-length compliance.
- [erstesbuch.de](https://erstesbuch.de): Guide platform for first-time book authors in Germany.
- [LachKartenManufaktur](https://lachkartenmanufaktur.de): E-commerce shop for handmade greeting cards.

### Client Projects

- [Sarina Rick](https://sarinarick.de): Portfolio website for the artist Sarina Rick.
- [Rainer Heidenreich](https://rainer-heidenreich.de): Author website for children's and young adult book writer Rainer Heidenreich.

### Content

- [BalkonkraftwerkExperte](https://balkonkraftwerkexperte.de): German-language guide and resource site about balcony solar systems (mini PV systems).

## Contact

- Website: https://niehu.es
- Email: stefan@niehu.es
- LinkedIn: https://www.linkedin.com/in/stefan-niehues-72542610/
- Mastodon: https://norden.social/@niehues
- Bluesky: https://bsky.app/profile/dnuc.eurosky.social

## Location

Oldenburg (Oldb), Lower Saxony, Germany