Payments backends at scale.
Now products with AI in the loop.
Three years running tokenized-payment services inside the Klarna App (500+ merchants, 40M+ users, on-call included), then subscriptions at Ivy. Since 2025: a voice dictation app with its own German speech model, a Kubernetes break/fix wargame, bots, agents, and the bare-metal infra it all runs on.
Product-shaped software, not tickets
Idea → prototype → users, usually alone, usually in a week. I keep the stack small so nothing blocks the next iteration.
- Apps: Android, desktop (Electron), web
- Bots & automation: Telegram, mail triage, scraping
- AI: agent harnesses, fine-tuned ASR, LLM eval
Tests, resets, and a written record
Every level in kaputt resets clean. Every deploy in soft-landing is blocked by Playwright. Every infra step is rehearsed in the cloud before touching metal.
- “Done is better than perfect” — then verify it
- Docs written while building, not after
- Claude Code as a daily pair, harnesses of my own
Production, then side projects
Weekly on-call for payment services at Klarna taught me what abstractions cost at 3 a.m. Subrosa is used daily by early-access testers, Hausbert found the flat I live in, Libertas runs a client's inbox.
- Available for freelance work, day-rate or project
- German / English, remote or Köln
Stack over time
What I was actually shipping with, per year. Filled points are things still in production.
Projects
Click a part for its spec sheet: what it is, how it works, the hard part, a live demo. Filter by material.
Timeline
From working student to on-call owner to my own products.
What you can hire me for
Four matched capabilities. Each has at least one shipped example above.
MVP in a week
Web, Android or desktop. Auth, payments, a backend that doesn't fall over. You get a URL, not a deck.
→ Subrosa, soft-landingLLM features that hold up
Agents, structured extraction, transcription, evals. With rate limits, fallbacks and a bias check.
→ Hausbert, LibertasAutomation & bots
Telegram, mail, scraping, n8n. Documented so your team can run it without me.
→ Libertas, KummerkastenSmall infra, done properly
A server that's locked down, backed up, and restorable. Rehearsed before it touches production.
→ infra, kaputtRecent activity
Pulled from the public GitHub events API on page load. If this is empty, I'm either on holiday or the rate limit hit.
Sections & gimmicks to add next
Things this page could do that a PDF can't. Marked by effort.
wg level 1 prints an incident, a few commands solve it. Teaches the product in 30 seconds.sudo anywhere and the page replies “Scared of pointers and doing the dishes.”