How do I find an exciting FOSS job during a pandemic?

Under normal circumstances, students and alumni would travel to Leuven from all across Belgium to meet companies that develop, support and/or heavily use Free and Open Source Software. Of course, that's not possible this year. To help anyone looking for a job, internship, student job or thesis arrangement, as well as the Belgian Open Source sector, ULYSSIS has created the directory below of curated open source companies who are currently hiring. Select the filters that fit your interests and skills, and then visit the resulting companies' websites to see what they're all about and what vacancies they currently have.

List of open source companies

Below you can find a list of companies offering jobs, internships, and/or student jobs in FOSS. All these companies are involved with Free and Open Source Software as developers, supporters and/or users. You can use filters based on your fields of interest and, if applicable, your preferred programming languages.


AI Data Science Desktop Graphics Development DevOps Document Repositories Embedded GIS IAM Network Research Security Sysadmin Web

Programming language: C C++ Go Java JavaScript PHP Python Ruby Scala

We use JavaScript to make it possible to randomize and filter companies, as well as show/hide descriptions and open links in either this tab or a new tab. We do not load any external JavaScript, CSS or fonts and don't use any frameworks, so your privacy is well protected while visiting this website, even with JavaScript enabled.

Spread the word

Want to help others find a FOSS job in Belgium? You can always help us spread the word! Post our website on your social media, email a link to some friends, write about us on your blog or mention it in a call.

Is your company missing on our list?

This year, we've made a selection of companies that we know well from past job fairs and that have visible information about FOSS on their website or careers page. While we do not plan to add more companies to this list, we are more than happy to welcome new companies at the next edition of the Open Source Job Fair in 2022. Our Job Fair offers companies with interesting and innovative FOSS jobs the opportunity to reach future graduates and young IT talent. So if you are looking for young FOSS innovators to join your ranks and wish to participate in next year's Job Fair, please contact us at

Who are we?

ULYSSIS is a student association from Leuven, founded in 1994. We started off with a single mail server, but in the meantime we have grown to a respectable organisation with about twenty servers. Our team is also still growing in numbers, just like the amount of services we offer. Our infrastructure hosts the websites of almost all student unions in Leuven, and more than one hundred associations, organisations, students and KU Leuven staff. Apart from that, we are increasingly offering technical support on events such as the 24 hour run and Beiaardcantus (carillon cantus), we give workshops to students who are interested in computer science and organise our own CTF. We do all of this under our motto “1 0 1, computer science for everyone”, and always with a focus on FOSS and Linux.


The ULYSSIS Open Source Job Fair was first organised in 2015. Since then, it has evolved, grown and matured. If you are curious about previous editions, you can find the posters and websites of all past years in our archive.