Current projects

Besides my client work, I maintain a number of my own projects. Here are the most notable ones:

• 

  Wishlephant

  Shortly before our kid was born, lots of people asked us what we needed as baby shower presents. We tried to organize it using email and an Excel sheet and quickly realized that this didn't scale. After looking into tons of gift registry websites, I realized that none had what I wanted and most of them looked really dated. So together with my wife I built Wishlephant, a wishlist and gift registry that was perfect for us. Wishlephant.com currently has around 60,000 unique visitors per month during the Christmas season.

  • Elixir
  • Stimulus.js
  • Postgres
• 

  Bookpile

  I love books and I love independent bookshops. When I wanted to recommend a book to a friend, I had no good way to point them to a place to get it. Bookpile.org solves that: enter an ISBN and it shows you nearby independent bookshops and libraries where you can get the book, along with links to it on book-tracking sites. It deliberately highlights small, independent bookstores over large chains. No affiliate links, no cookies, no tracking - just books and the places that sell or lend them. The code is open source and can be found on Codeberg.

  • Elixir
  • Phoenix
  • Postgres
• 

  Hier Baut Berlin

  Hier Baut Berlin informs citizens of Berlin about changes in their neighborhood: street construction, new bike paths, or ways to participate in key decisions in the neighborhood. I built it as part of the 9th round of the Prototype Fund, a German public funding program for open-source software, and continue to maintain it.

  This information used to be scattered across 20-30 different pages. Hier Baut Berlin shows all of it on one map. You can also subscribe to changes via email, so you never miss an important update.

  The code can be found on GitHub.

  • Elixir
  • Stimulus.js
  • Postgres
  • Pd3f
• 

  Papi Berlin

  I founded Papi Berlin, a Berlin-based community for active fathers* (the asterisk stands for everyone in a fathering role), dedicated to redefining fatherhood beyond traditional gender roles. The group promotes concepts like mental load awareness and needs-oriented parenting. It offers a supportive network through an active Slack channel, where fathers can exchange ideas, seek advice, and share resources on topics such as parental leave, daycare, and parenting challenges. The platform also features blog posts covering family life, educational transitions, and media recommendations.

  • Parenting
  • Dads
• 

  SignDict

  SignDict.org is one of the leading dictionaries for the German Sign language. 95,000 unique users per month use the site to learn this wonderful language. I built this site as part of the first round of the Prototype Fund and continue to maintain it. The code can be found on GitHub.

  • Elixir
  • Vue.js
  • Postgres
  • Redis
  • FFmpeg

I also maintain a couple of smaller open-source libraries and tools. Check out my Codeberg and GitHub profiles for a complete list.

Past projects

In over 20 years of working in the tech industry, I participated in numerous projects. Here is a small list of things I am proud of.

• 

  Airy

  From 2018 till 2021 I was freelancing for Airy as part of their React frontend team. Airy is an open-source platform that lets companies talk to their customers through a website live chat, Facebook Messenger, WhatsApp and other messaging channels, all from one place.

  The code can be found on GitHub.

  • TypeScript
  • React
• 

  Sloth Emoji

  An emoji? Yes! Did you know that you can write a proposal for Emojis? I got lucky and my proposal for the sloth emoji was accepted, and since 2019 the sloth can be found on every phone and laptop 🎉.

  I hopefully made the world a better place with adding the 🦥 emoji. Also want to create an emoji? Join the emojination slack, and they will help you make it happen.

• 

  bitcrowd

  For a couple of years I was a co-owner of bitcrowd, a Berlin-based web agency. During my time there we helped many startups become successful businesses. We built the first code for startups like time:matters, Liefery, Krautreporter and many more.

  • Ruby on Rails
  • Angular
  • React
  • Postgres
  • Redis
• 

  putpat

  From 2009 till 2013 I was part of putpat.tv. Putpat, which has since shut down, tried to re-invent music television for the modern internet age. With over 50,000 videos and a smart algorithm to create channels based on your taste profile it was loved by a huge user base. Since it was a relatively small team of developers, I was responsible for many client applications, from software that ran on TVs to Android and iOS apps. Besides that, I built parts of the ingestion and tagging platform.

  • Ruby on Rails
  • JavaScript
  • Objective-C
  • Java
  • Postgres
  • Redis
  • FFmpeg
• 

  TV-Browser

  TV-Browser is an open-source desktop TV guide, written in Java, for more than 1,000 TV stations. I was the lead developer till 2011 and at its peak it had over 150,000 active users. The code can be found on SourceForge.

  • Java
  • Swing