Sopra Steriawww.soprasteria.com
Application architect at one of Europe's large IT consultancies, building enterprise systems for clients.
I build enterprise systems for a living, and my own on the side since 2006.
All still running
Employed since 2014
Founder since 2017
Teamhubwww.teamhub.de
Management software for clubs and associations, used by Letzte Hilfe, Advance Care Planning international and the Schweizerische Gesellschaft für Biomedizinische Ethik across Germany, Switzerland, Austria and beyond.
I founded Teamhub, wrote it from scratch and have run it ever since.
It covers membership administration, fees and payments, document generation and newsletter delivery, in German, English and other languages.
Changes are deployed continuously, and only after the full automated test suite has passed.
- > €200,000
- membership fees processed
- > 100,000
- lines of PHP
- > 2,000
- automated tests, green before every deploy
- > 200
- schema migrations against live customer data
- 9 years
- in production, same codebase
Challenges
- Real payments from all over the world. Real money moves through Teamhub, straight into the organisation's account. In a volunteer association every euro counts: a direct debit costs cents rather than a percentage.
- One codebase, no rewrite. Teamhub started in 2017 on PHP 5.5 and Symfony 3.3. It runs on PHP 8.5 and Symfony 8.1 today, through every major version in between: the same system, carried forward, never replaced by a second one.
- Separate data controllers, one deployment. Every organisation is its own data controller under the GDPR. They all run on the same installation, and the architecture is what keeps their data strictly apart.
On stage
At the Last Aid Conference 2026 I talked about the processes behind Last Aid courses, and how Teamhub supports the people who organise them.
Photos: Karin Gruber
Other projects
For clubs and associations
Plan-your-eventswww.plan-your-events.com
Organise your club's events without spreadsheets or sticky notes: one page per event, sign-ups confirmed by email, seats and waitlist at a glance, and the participant list ready to download. Along the way you build a newsletter list, so you can tell everyone about your next event.
Guests never create an account: the confirmation link in the email is their identity. Somebody who attends one event in their life should not have to register for a service first.
Online since 2022, hosted in Germany, without tracking, and free.
For people learning languages
JLPT-Infowww.jlpt-info.org
Will you pass the Japanese-Language Proficiency Test (JLPT)? Calculate your chances and estimate how long it takes you to reach the next level.
For people learning languages
Tensakuwww.tensaku.de
Write Japanese, understand your mistakes. An AI checks your text sentence by sentence and explains every spot. The rewriting you do yourself - that is the only way it sticks.
For people learning languages
Gengowww.gengo.de
Co-founded in 2006 and online ever since. An interactive platform for German students of Japanese, built around the textbook Japanisch im Sauseschritt, the German edition of Japanese for Busy People. With our app you can learn the Japanese alphabet on your phone.
For biology and chemistry students
Aminoswww.aminos.org
Learn the 20 proteinogenic amino acids. The idea goes back to my own studies in 2007 and the app keeps improving.
For anyone with a music collection
Spinmusicwww.spinmusic.de
A music player for your local library that runs in the browser. Edit metadata, manage cover art, and write lyrics and time them right from the player.
No server, no database, no account: the browser reads your folder directly and writes every edit back into the files themselves, so the collection stays yours and moves with you. The price of that decision is that it needs a Chromium browser.
For a few minutes with friends
Fencelinefenceline.mathiasbader.de
A multiplayer browser game. Draw lines, claim land, set it on fire.
Share the address to play with friends.
Firsthand
“With Teamhub we are able to bring a worldwide community of doctors, caregivers, academics and activists together”
“I come from IT and know how involved software like this can get. All the more reason I value how plainly and cleanly this is done: create the event, send the link, that is it.”
“Teamhub saves us time and therefore creates space for things that really matter”
“We used to collect the registrations for our events by email and telephone. Today we announce a link, and on the evening of the event the participant list is simply there. On top of that we can see at any time how many guests have registered. That gives us certainty in our planning.”
“Teamhub helps us empower our national and international network. Solution orientation, efficiency and service are exemplary.”
“Our courses are often booked out quickly. The waiting list fills by itself, and when somebody cancels the next person moves up, without us keeping any lists.”
