Available full-time from December 2026. Get in touch.
Senior engineering power for startups and small software teams. Shipping from week one.
I'm a freelance software engineer based in Germany, working fully remote. I join your team and own features end to end, from shaping requirements with stakeholders to deployment. My home is the backend: Java, Spring Boot, and AWS. If a feature needs frontend changes, I don't stop at the API. As a former CTO and Principal Engineer, I keep the business goal in sight. I'm not done until it runs in production.
AI writes code fast. Someone still has to make sure it’s the right code: maintainable, reviewable, and stable in production. That’s my job. I’ve driven large-scale migrations, shaped company-wide standards, and mentored 30+ engineers.
At heart I’m still a craftsman, and that’s why I use AI the way I do. It makes me faster and a sharper thinker, not a passenger. Every trade-off and every line that ships goes through me first. The leverage is new, the ownership isn’t.
Breaking software since my C64 days, fixing it professionally for 14 years. Grounded in a Ph.D. in Computer Science and a strong background in mathematics.
What I take on
Feature Delivery
I join your team for 3 to 12 months and take features from requirements to production. Your stack, your process, my ownership.
Stability & Cost
Production issues, slow systems, rising cloud bills. I find the root cause and fix it, like cutting database costs by 30%.
Team Enablement
Pairing, code reviews, and test strategy that make your team better. Including how to use AI-assisted engineering without losing control of the codebase.
What they say
"Dr. Lesniak delivered excellent solutions for complex technical and business product requirements. The source code is very well structured and documented."
Jonas Danker, CTO, Micromerce
"His ability to quickly grasp complex requirements and translate them into robust solutions significantly advanced our team."
Vincent Sommer, Head of Engineering, milia.io
Need senior backend capacity for your team? Let's talk.
Or call me: +49 151 551 69 221
Outside of work I play chess, climb indoors (bouldering and lead climbing up to 16m walls), read science fiction, and explore the German countryside with my dog Suki.