Type-safe by default
TypeScript end to end. Strict mode on. Schemas at the edges. The compiler catches what tests will not.
TD
About
Senior fullstack engineer. 14 years of enterprise contracts.
I'm Tristan Döhl, a senior fullstack developer based in Aachen, Germany. For 14+ years I've been building enterprise software — from React frontends to Elixir backends to Kubernetes infrastructure.
Currently I'm building AI-powered features at SAP. Before that: welding robot software at my own startup, a 50,000-line TypeScript migration at DKMS, and onboarding systems at Ribbon Home.
Career
Selected roles, 2011 to present
- 2025 → presentSAP — AI features for enterprise products
- 2023 → 2025Plasma Additive — Founder, CNC welding robot software
- 2020 → 2023DKMS — 50,000-line TypeScript migration lead
- 2018 → 2020Ribbon Home — Onboarding systems and tooling
- 2011 → 2018Various enterprise contracts (frontend, backend, infrastructure)
How I work01 02 03 04
Four principles I will not compromise on
Ship in iterations
Two-week blocks, Friday demos, code in a real branch. No three-month silent sprints ending in surprise.
Document the why
Code says what. Comments and ADRs say why. Your team six months from now thanks me for this.
Own the full stack
Frontend, backend, infrastructure, monitoring. No throwing problems over the wall to someone else's team.
On the internet
HolyMarcell, same person since 2010
My code lives at github.com/HolyMarcell — I've used this handle since 2010. The work and the name are the same person. If you found a Stack Overflow answer, an Elixir library, or a CSS Houdini paint worklet under that name, that was me.
github.com/HolyMarcellPixel-me from 2021 — still living rent-free in this codebase.
Next step
Let's work together
30-minute intro call. No sales pitch. We figure out whether we are a fit, fast.