Johannes Filter
Photo: Julia Bornkessel · CC BY 4.0 · Download full-size
About

Johannes Filter

Freelance full-stack developer and CiviCRM specialist based in Berlin.

I build data-driven web applications with Next.js, React, and Django — and I help nonprofits and NGOs adopt and extend CiviCRM, an open-source CRM that fits their budget and constraints.

Most of my work is with civic-tech organizations, journalists, and researchers — people who need reliable software without the glossy agency price tag. If CiviCRM or a custom build is the wrong fit, I’ll tell you. Bad-fit projects help no one.

I hold a master’s in computer science from the Hasso Plattner Institute, with a focus on data visualization, machine learning, and NLP. I contribute to open source on GitHub and write on my blog when I learn something worth sharing.

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

2025
How Mastodon works — an introduction to the decentralized social-media alternative DE
Publix Open House · with Zora Steiner (Mastodon gGmbH)
Slides
2023
Mit DSGVO gegen TikTok: how to push back against tech platforms DE
OK Lab Berlin
Recording · 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 →