Principal Product Manager · Berlin
I get to the bottom of complicated systems, then build them and explain them plainly.
Twenty years of product management on consumer apps, e-commerce and regulated platforms, for Douglas, ON, Eurowings, Trusted Shops and A1 Telekom. Today I’m Principal Product Owner at Sonova. On the side I’m building an AI product where every answer has to show its source.
- Now
- Principal Product Owner, Sonova
- Before
- Trusted Shops, ON, Douglas, Eurowings, IONOS
- Looking for
- Senior and principal product roles in applied AI and the energy transition
In numbers
What the work added up to.
- €1B+Annual revenue running through the Douglas iOS and Android apps I ownedDouglas · 2020–21
- 0Minutes of downtime while those apps moved to a new SAP Hybris backendDouglas · 2020–21
- +50%Conversion on a BaFin-regulated investment platform, after lab usability testingWIWIN · 2022–23
- #1App Store ranking for brand keywords in 10 markets, rating held at 4.7 through a rebrandTrusted Shops · 2025–26
- 250kUsers within weeks of launching a secure messenger on iOS and AndroidIONOS · 2016–17
- 1MUsers on a bootstrapped dating app I co-founded, with a #1 Google rankingM47 Interactive · 2009–15
Selected work
Four case studies, each a different kind of hard.
- 01 Douglas · Retail appsMoving a billion-euro app business onto a new backend without a minute of downtime 0 downtime4 Scrum teams, 40+ people, millions of customers
- 02 WIWIN · Regulated fintechMaking a BaFin-regulated investment flow feel safe enough to finish +50% conversionKYC, payment and tokenization in one journey
- 03 Trusted Shops · Consumer appsGrowing a consumer app through 30,000 partner shops +27% sign-ups#1 for brand keywords in 10 App Store markets
- 04 Redline · Own AI product, in buildAn AI contract reader that has to prove every claim it makes 100% citedEvery risk flag quotes its source sentence, checked in CI
On AI
I’d rather show you than claim it.
Most of my career came before large language models, and I haven’t yet shipped an AI feature to paying users. I’d rather you read that here than work it out from my CV.
So I’m learning AI the way I learned every domain before it, from BaFin rules to the financing rules for solar modules: by going deep enough to build the thing myself, and writing down what I don’t know yet.
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Redline, an AI contract reader
I wrote the research, the PRD and ten architecture decisions. Coding agents built the tickets against them. The build gate: every risk flag must quote a real sentence from the document, verified in CI.
Read the case study -
Automation in daily product work
n8n workflows and Claude tooling at Trusted Shops, alongside owning the apps and the web portal.
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An agent workspace for my own job search
I run my search on a Claude Code workspace and have extended it with research on about a hundred target companies. Building on it is how I learn where agents help and where they quietly make things up.
Before apps: solar
Energy isn’t a new interest for me.
From 2008 to 2012 I ran two companies importing photovoltaic modules from China by the container, selling direct to installers and EPCs in Germany and Italy. German banks wouldn’t finance installations with unknown module brands, so I set up the reference projects they needed and took two brands to bankability.
- ~€1Mannual revenue
- 2brands made bankable in Germany
- 2markets, sold direct to installers
Record
Where I’ve worked.
| Years | Company | Role |
|---|---|---|
| 2026 – | Sonova | Principal Product Owner |
| 2025 – 26 | Trusted Shops | Principal Product Manager, D2C apps and web portal |
| 2024 – 25 | ON | Principal Product Manager, D2C e-commerce app |
| 2024 | Lotto24 | Principal Product Manager, freiheit+ launch |
| 2022 – 23 | WIWIN | Principal Product Manager, investment platform |
| 2020 – 21 | Douglas | Principal Product Manager, Retail Apps |
| 2019 | Eurowings Digital | Senior Product Owner, Digital Services |
| 2016 – 17 | IONOS | Product Manager, Mobile Messenger |
| 2013 – | A1 Telekom Austria | App supplier, project and product management |
| 2009 – 15 | M47 Interactive | Co-founder, Product Manager Mobile Apps |
| 2008 – 12 | BSL Greentech, Felix Solar | Founder, PV module import |
| 2005 – 08 | Jamba! | Product Manager Mobile |