This one is AI generated. I'm bad at draw & I liked this pic, sorry :(

Well, so I was at fosdem 2025 all weekend. It was my first time here, and I thought it would be nice to write a little guide for people who wanted to go there but who have never been there and are wondering what to look out for !

Keep in mind that Brussels weather is weird !

Sooo... Make sure you have suitable clothing. In Belgium in February, the temperature varies but it's often very cold. It can sometimes rain a lot. So make sure your clothes are warm and rainproof! You'll also have to do a lot of walking (sometimes running lol) between the buildings, and some of them are quite far apart, so take appropriate footwear.

Install compagnion app

Fosdem contains a huge number of conferences, so you'll need a place where they're all listed. An application like this will keep you on track, tell you what conferences are coming up and where they are in the buildings. You'll find a list here; I use Fosdem Compagnion.

Plan ahead for the conferences you want to see, but...

...Remember that you're bound to miss some. Fosdem attracts thousands of people, and even with good forethought, some rooms will be completely full, and you may not find the room where your conference is taking place in time. So really click on what interests you, and leave some time between conferences so you don't end up running around !

The ULB site is vast. So don't hesitate to ask for a map, they probably have some at the infodesk in building H, which is in the main alley on the right.

Almost all conferences are recorded, and available after the event on the FOSDEM website. So don't worry about what you missed!

Taking notes, electricity and wifi

You may want to take a laptop or tablet to take notes. But you'll find very few outlets... So take an external battery too. And a notebook, you never now ! And wifi is not available everywhere: in my experience (which may not be up to date), you'll probably get good reception in the H, K and J buildings, but not in some parts of the U building, and almost nothing in the UW building. So make sure you also have a good internet forfait.

I didn't have an external battery on site, so it was complicated to recharge my old laptop, which lasts 1h30 unplugged... I ended up taking notes on my phone and on paper, but I more or less managed anyway x)

There are several sockets at the end of the corridor when you enter building J from building H, and they're often not used, so they can be useful!

Food (om nom nom)

Take food. Not because there aren't any food spots, but because there will be monstrous queues to buy it, and unless you like to queue for 1 hour before eating, take something to eat! Take a reusable water bottle too; tap water is in most cases drinkable in Belgium, so tap water on the ULB campus is too!

Also, don't drink too many beers, and watch your alcohol intake: Belgian beers can sometimes be quite strong. You probably don't want to end up ripped off...

I think I've pretty much said it all, so please don't hesitate to point out any mistakes I've made (especially with building names...). Don't forget to get in touch with the people you meet at this event, because it's very enriching. And just enjoy FOSDEM, when you can be there !