stupid layout fix
Stefan Wille

Work

My professional career started in 1996. This gives me 30 years of experience.

In my first Job, I joined Netlife. Eventually I became Netlife's vice president of product development and stayed until after their IPO.

In 2009, I cofounded Balao, the company who built GratisPay, and worked as its CTO. We sold Balao in 1/2010 to Fyber.

From 2010-2013 I was CTO and cofounder of Papersmart GmbH.

Today I work as a freelance senior full-stack engineer with a focus on TypeScript, React, Node.js, and AI integration.

Since 2012 I live and work in Berlin.

Areas of Interest

I am most interested in

  • TypeScript, React, and Node.js
  • AI engineering and agentic development
  • Collaboration with customers and colleagues
  • Better ways of working together: Automated testing, simple code, self organization, Domain Driven Design (DDD)

Experience

Frontend Developer | 03/2025 – 12/2025
Lead Fullstack Developer | 10/2022 – 04/2024
Lead Frontend Developer | 07/2020 – 09/2022
Lead Frontend Developer, Coach | 09/2019 – 03/2020
Frontend Developer | 01/2019 – 08/2019
Frontend Developer | 10/2018 – 12/2018
Fullstack Developer | 09/2018 – 10/2018
Frontend Developer | 04/2018 – 05/2018
Fullstack Developer, Coach | 04/2017 – 03/2018
Frontend Developer | 01/2017 – 01/2017
Fullstack Developer | 06/2016 – 12/2016
Lead Frontend Developer, Scrum Master | 03/2016 – 05/2016
Lead Backend Developer | 08/2015 – 12/2015
Backend Developer | 07/2015 – 08/2015
Architecture, Development | 11/2014 – 01/2015
Teamlead, Backend Developer, Scrum Master | 04/2014 – 10/2014
Backend Developer | 11/2013 – 03/2014
Backend Developer | 09/2013 – 03/2014
CTO, Founder | 09/2010 – 05/2013
CTO, Cofounder | 04/2009 – 02/2010
Team Lead Backend | 10/2006 – 02/2009
Backend developer | 05/2006 – 09/2006
Analyst, UI Developer | 02/2002 – 05/2004
VP Research & Development | 01/1996 – 05/2000

Projects

  • Billet – CLI coding agent built directly on the Anthropic SDK: agentic loop, bash and text editor tools, plan mode, eval suite (TypeScript, Anthropic SDK, Bun) – GitHub
  • Smart Rename – AI-powered desktop app that extracts invoice metadata and auto-renames files (Vercel AI SDK, Evalite, Tauri, TypeScript, React) – stefanwille.com/smart-rename
  • Recto – published web tool for planning book page layouts, in production use on a 400-page book project (TypeScript, React, Supabase) – rectostudio.com

Open Source

  • Anki MCP Server - enables LLMs to generate and correct flashcards: GitHub
  • A TypeScript / React implementation of the game Pac Man: GitHub
  • A Redis client library in Crystal: GitHub

Mentoring

  • I used to mentor a junior developer before her first job and then while she worked her new employment.
  • During Covid I have mentored a another aspiring developer, who is now working as an intermediate-level developer.

Books

I have written two books:

The first book is "Go To JavaServer Pages". Addison Wesley published it in 2001. At the Amazon page you can find an overview and reader reviews.

Cover of the book Go To JavaServer Pages by Stefan Wille

My second book is "Spring and Hibernate". It introduces Spring and Hibernate, and how these two technologies play together in a typical project. Please see Amazon's page. Hanser published the second edition in April 2008.

Cover of the book Spring and Hibernate by Stefan Wille

Certifications

2006 CSM – Certified Scrum Master

Education

Bachelor at University of Hamburg:

  • Major in computer science (distributed systems)
  • Minor in business economics

Hobbies

  • Argentine Tango
  • Italian
  • Fitness