Johannes Filter
About

Johannes Filter

Developer in Berlin. Web tools for research, CiviCRM for nonprofits.

I am a developer in Berlin. I build web tools for journalists, researchers and NGOs, and I run CiviCRM for nonprofits that want a CRM without a vendor attached.

I got into this through freedom-of-information work. Around 2017 I started filing requests with German authorities for FragDenStaat, and the documents that came back needed scraping, cleaning and publishing. Three Prototype Fund grants, three years at AlgorithmWatch and a lot of side projects later, that is still roughly what I do, just with clients.

I studied computer science in Magdeburg and at the Hasso Plattner Institute in Potsdam. My code is on GitHub, and I write on the blog when something took me longer to figure out than it should have.

Experience

2024 —
Freelance Full-Stack Developer
Building data-driven web applications with Next.js, React, and Django. Also helping nonprofits set up and customize CiviCRM.
Development · CiviCRM →
2020 — 2023
Software Developer and Data Scientist, AlgorithmWatch
Built DataSkop, a browser extension for crowdsourced platform research.
2019 — 2020
Full-time Open-Source Developer, Prototype Fund
Three grants from the German government for Kommentare, pd3f, and Tatort Rechts.
2017 — 2020
Journalistic Contributor, FragDenStaat
Filing, managing, and analyzing Freedom of Information requests to German public bodies.

Education

2016 — 2019
Master of Science, Computer Science, Hasso-Plattner-Institute
University of Potsdam.
2016 — 2017
Exchange student, Human-Computer Interaction, Tallinn University
Estonia.
2015
Research internship, U.N.E.D.
Universidad Nacional de Educación a Distancia, Madrid.
2011 — 2015
Bachelor of Science, Computer Science, Otto-von-Guericke University
Magdeburg.
2016 — 2019
Scholarships
Studienstiftung des deutschen Volkes (German Academic Scholarship Foundation) and Deutschlandstipendium.

Selected talks

2026
Data donation as a weapon: how we can use the GDPR to pressure Big Tech DE
re:publica 26
2025
How Mastodon works — an introduction to the decentralized social-media alternative DE
Publix Open House · with Zora Steiner (Mastodon gGmbH)
Slides
2020
Warum automatisierte Filter rassistisch sind DE
95. Netzpolitischer Abend der Digitalen Gesellschaft @ c-base
Recording · Alternative recording · Slides
2019
Broken Beyond Repair — No Patch for Verfassungsschutz: a critical analysis of the yearly German intelligence-agency reports DE
ChaosWest @ 36C3
Recording · Alternative recording

All talks →

In the press

2023
Netzpolitik.org DE
“TikTok: AlgorithmWatch ruft zu Datenspenden auf”
2021
bpb Podcast DE PODCAST
“Netz aus Lügen – Die Netzwerke (5/8)”
2021
Netzpolitik.org DE
“Bayern geht gegen Open-Data-Aktivist:innen vor”
2021
Deutschlandfunk DE RADIO
“15 Jahre Informationsfreiheitsgesetz”
2021
Netzpolitik.org DE
“Tatort Rechts: Neues Projekt sammelt rechte Gewalttaten auf interaktiver Deutschlandkarte”
2020
Netzpolitik.org DE
“Sprachalgorithmen – Die Diskursmaschine”

All press →