Hi, I'm Johannes Filter.

I'm a Berlin-based freelance software developer and data scientist. I'm interested in data visualization, machine learning and natural-language processing. Until recently, I've been working for the nonprofit AlgorithmWatch to reverse engineer large tech platforms via crowdsourcing. Besides, I hold a master's degree in computer science from the Hasso Plattner Institute.

I'm an activist for more transparency in the public sector and I'm part of the German open data / civic tech / freedom of information community. I write about my investigative reporting using German FOIA laws on ifg.jfilter.de (in German).

Because I still believe in the liberating effect of open-source software, I regularly contribute to it on GitHub. Also, I have a programming blog (in English). You can find more information about myself in my CV.

Check out my previous work, see what services I offer, and follow me on Mastodon or Bluesky.