Reflections on FOSDEM ‘25

From the minds of Teppo Suominen, Lewis Torrington, Nate Ham, Toni Peltonen, and Werneri Aarnio 🧠

This year marked an incredible 25 years of FOSDEM 🤯. Host city Brussels even put on three days of winter sunlight in celebration. (Or maybe that was just luck…) We headed down to Belgium to soak up the innovations, projects, and a beer or two. Here’s our reflections on 48 hours of pure engineering joy:  

What’s it all about?

FOSDEM is a two-day event organised by volunteers to promote the widespread use of free and open source software, and, according to the organisers, is widely recognised as the best such conference in Europe. We fully agree. Attending FOSDEM is an absolute must for any engineer. 

This year’s event featured 1193 speakers, 1104 events, and 79 tracks, across 35 different rooms. Yep – it’s huge.  

“It’s chaos from top to bottom. Embrace it” – Teppo Suominen

2025 Themes & Trends 

Learning directly from highly experienced and passionate practitioners is one of the things that makes FOSDEM so special. Among the many Dev rooms, we spotted some trends this year: how open source is faring in the EU legislative landscape, and why we all need to write better docs. 

OSS in EU Legislation 

It was interesting to see how open source is evolving in the European legislative landscape, and there were multiple policy tracks and talks discussing topics like the Cybersecurity Resilience Act (CRA), AI Act, and Digital Services Act. 

• Legal and Policy
• SBOMs
• EU Policy

Docs, Docs, and more Docs

Documentation was a core theme throughout multiple Dev rooms – from talks about how to improve quality, to breaking down how to write better docs and get people engaged with your projects through documentation.  

• The state of eBPF docs
• Tool the Docs

UpCloud’s FOSDEM survival guide

This wasn’t our first rodeo, but the sheer size of FOSDEM is still pretty overwhelming. Here’s the tips and tricks we’ll be leaning on in 2026!

Get there early

Figure out what talks you want to attend in advance. One look at the schedule for FOSDEM and you’ll quickly see that it’s impossible to get to everything. Remember you can catch the talks online. 

Also, make sure you get to the designated Dev room in plenty of time, because popular talks will fill up fast. You can wait and queue outside, or even just follow other devs’ lead and watch the presentations online, in the queue!

But also, get outside the venue!

There are a lot of people at FOSDEM. A lot. And the air quality is not great in the older campus buildings. Be warned!

Check out the FOSDEM Fringe site a few weeks before the event, to see what side quests are open – and make sure you sign up! Places fill up fast. We hosted a happy hour the night before FOSDEM and met folks from all across the world over some beers. Other communities even host mini conferences and hack days.

Get the stickers

FOSDEM is a great opportunity to meet folks who are building and maintaining the projects you use everyday. We met the WireGuard team ❤️ (among many others!) while hunting for stickers. So just bowl up and start chatting – everyone is welcoming and friendly. 

Some of our favourite 2025 talks, tracks, and project finds  

“The quality of the talk is inversely proportional to the amount of effort spent styling the slides.” – Lewis Torrington

Talks

• From Queries to Pints: Building a Beer Recommendation System with pgvector

Tracks

• Retro Computing
• Radio 
• eBPF
• Design
• Community 

Project finds 

• https://github.com/unitaryfund/ucc
• https://elv.sh/
• https://boxer.dev/

Finally…

“Belgium has the best waffles in the EU. Confirmed.” – Werneri Aarnio