FOSDEM 2025: A Weekend of Talks, Conversations, and Controlled Chaos

My first FOSDEM has come and gone, and what a whirlwind it was! Over 8,000 attendees, more than 1,000 talks, and 70 parallel tracks—all squeezed into two intense days, where no matter where you stood, you were never more than five minutes away from a place serving strong Belgian beer. It’s an overwhelming, exhilarating, and utterly unique experience that truly embodies the spirit of Free and Open Source Software (FOSS).

Two Talks, Two Days, and a Lot of Running

This year, I was fortunate (or foolish?) enough to give two talks at FOSDEM, covering topics close to my heart:

• “LHC Analysis Preservation Using Rivet” (Open Research Track)
• “HPC-Friendly Histogramming in C++ Using YODA” (HPC, Big Data & Data Science Devroom)

Both talks sparked some great discussions, and it was fantastic to see so much interest in open-source tools for high-energy physics. From talking about the challenges of preserving LHC data analysis for future re-interpretation to discussing efficient histogramming techniques for massive datasets, I was reminded again how vibrant and diverse the FOSS community truly is.

Logistics-wise, I got lucky—my talks were on different days, so fortunately, I didn’t have to dash between venues to make back-to-back sessions. But even without that added chaos, FOSDEM is always a test of endurance, between navigating the packed hallways, grabbing quick meals on the go, and balancing the desire to attend interesting sessions with the equally rewarding experience of impromptu hallway conversations.

The People You Know (But Have Never Met)

One of my favourite aspects of FOSDEM is the chance to finally meet people in person who I’ve only known via email or social media. This year, a particularly memorable moment was bumping into Stephanie Taylor, who runs the Google Summer of Code (GSoC) initiative. We had a lovely chat about the ongoing challenge of keeping great initiatives like GSoC funded and the importance of celebrating and selling short-term success stories to sponsors. Her insight was a valuable reminder that impact isn’t just measured in lines of code but in the doors opened for early-career developers and researchers.

Beyond scheduled talks, the sheer number of FOSS projects, tools, and ideas on display was staggering. I found myself jumping between sessions on everything from scientific computing to container security, absorbing as much as I could while also trying to save some brainpower for post-conference write-ups like this one.

Looking Ahead

FOSDEM is a reminder of how much the open-source world thrives on collaboration, curiosity, and community. Whether it’s through hacking on Monte Carlo tools, sharing best practices for software sustainability, or simply catching up with colleagues over a Belgian beer, these gatherings reinforce why FOSS is such an exciting space to work in.

If we chatted at FOSDEM, it was great meeting you! If not, maybe next year? Also, if you missed my talks, you can now watch them online:

• LHC Analysis Preservation Using Rivet
• HPC-Friendly Histogramming in C++ Using YODA

Until next time! 🚀