About

Hello! I’m Stéphan. I am a Machine Learning engineer. Welcome to my personal website. I hope you enjoy reading it. If you have any questions or comments, feel free to reach out through my social channels, or via e-mail. None of the stuff I write is generated, although I do use models for writing checks/hints.

Professional

I work as a principal ML engineer at Ecosia, the search engine that plants trees. In this role I do a lot of different things, including logging/alerting, training models, writing typescript code for agentic stuff, product work, etc. I consider myself to be an end-to-end ML engineer; I know how to wrangle data, train models, but also how to put them in production and how to think about getting things into production. I am happiest when I am included in the product side of things; a kind of internal ML consultant.

I am one of the founders of minish, and created model2vec, semhash and the potion models. I quit Minish in september 2025, I just thought it wasn’t that fun any more.

Before going into industry, I was a ph.d student at CLiPS, the Computational Linguistics and Psycholinguistics Research Center at the University of Antwerp in Belgium. My thesis topic was on the psycholinguistics of lexical access and word recognition. I defended my thesis remotely on the 11th of September 2020.

Research

From a research perspective, I am mainly interested in:

• Tokenization: I think this is one of the most underresearched but fundamental areas of modern machine learning models.
• Small models: I co-created the world’s smallest best models, the potion models.
• Search and retrieval: search is going to be important and stay important in the foreseeable future. No matter how big models and their context sizes get, you will always be able to have more data than you can fit, or will be able to save money by efficiently retrieving the right data.
• Typing systems, and how to write secure code for interpreted languages. I love thinking about types, and how making better types leads to safer code.

If you think any of these topics sound interesting, feel free to reach out. I like working on things and will do so for free if it’s interesting and will be open sourced.

Personal

• I live in Antwerp, Belgium, with my partner and 2 children
• I love closely listening to music, across all genres.
• I love reading, mostly science fiction. Jeff Vandermeer and China Miéville are probably my favorite authors.
• I work remotely, and, with the exception of some brief excursions into local coffee places, spend most of my time at home
• I love coffee, pickles, and hummus