About

I like starting from a client need, turning it into a product that runs, then changing it without breaking it. New builds and legacy code alike: taking over code left abandoned, or keeping a product that already runs alive. Python backends, CI/CD pipelines, declared infrastructure, and security handled from the design rather than after the incident. What I do not know, I would rather say than dress up.

The platform I run alone

Interview Challenger turns a job-offer URL into an interview-preparation site: fetch the offer, research the company, plan the pages with an LLM, build a static site, publish it behind a password. I designed it, built it and I operate it alone. What is not automated, I do by hand, and nobody takes over when I sleep. That is why the pipeline matters more than the code: it decides what ships. Images are tagged by commit, deployment pull requests are opened for me, and production waits for a human.

The dataset that outlived the code

For five years I was lead engineer on Jaccede, a national accessibility platform run by a non-profit. We rewrote an outdated stack and moved it to AWS without stopping it, built the Flask API that made the data consistent, and kept a collaborative dataset free of duplicates. The subsidies were no longer enough and the site closed in December 2024. The S3 backups and the RDS instance were deleted. The Internet Archive had indexed the site since 2002, but the product was a SPA: the archived HTML is a shell and every archived API response is a 403. There is no dump to recover. I had helped structure that dataset, so I rebuilt it as LetMeGetIn from the private repositories that survived: a public read-only API in FastAPI, PostgreSQL with PostGIS, an admin CLI as the only write path. The community side is not built. It is a start, not the platform that disappeared.

English as the working language

In 2013 I went to New Zealand for a year. I spent several months at Treshna Enterprise in Christchurch on web and mobile projects for several clients, with no possibility of falling back on French: no asking for a clarification in my own language, no recovering a sentence that went wrong. That is where English became a working language rather than a line on a CV. Since 2020 it has been the language of every day: six years at UKG and then Back Market, international teams, code reviews, incidents and documentation in English. My last two managers did not speak French, and every meeting was in English. The CV says fluent; that is what it means, not a test score.

Outside the CV

What I do outside the CV. No lesson attached.

  • Outdoors. Gardening, Climbing, Hiking, Cycling.
  • With my hands. DIY, Repairing objects, Tinkering with computer hardware.
  • In my head. Chess, Cybersecurity, Hacking.
  • On stage. Theatre, Improvisation.
  • With my children. Looking after my children.

Contact

Based in Belgium, near Liège, working remotely with teams across Europe. If a system needs stabilising, a product needs shipping, or a decision needs a second opinion, write to me.

contact@sebastienbillion.dev