Developer tools and infra is the one vertical that already clears the Tier B floor – 28 qualifying regional developer conferences across Central and Eastern Europe, Scandinavia and Western Europe, even though only one show (FOSDEM) reaches Tier A scale.
1Rank
Devtools, open source infra 30 Jan 2027, Brussels 8,000 attendees
Europe's largest free and open-source software developer conference, run by volunteers on the ULB Solbosch campus.
Why it is hereThe single biggest open-source developer audience in Europe, and free to attend.
2Rank
Devtools, open source infra, testing and CI 7 Apr 2027, Paris 4,500 attendees
The French edition of the Devoxx developer-conference franchise.
Why it is hereThe largest French-market developer audience on the circuit.
3Rank
APIs, devtools 13 Sep 2026, Zadar 4,000 attendees
A developer conference run by Infobip, covering APIs and communications infrastructure.
Why it is hereStrong API and infrastructure-tooling focus, with a distinctive Croatian coastal setting.
4Rank
Devtools, testing and CI 5 Oct 2026, Antwerp 3,500 attendees
The original and largest Devoxx conference, held annually in Antwerp.
Why it is hereThe flagship event of the Devoxx franchise, with the deepest Java and JVM-ecosystem audience.
5Rank
Devtools, open source infra 28 Oct 2026, Milan 3,000 attendees
A multi-language developer conference covering the full software stack.
Why it is hereThe strongest Italian-market developer audience.
6Rank
Open source infra 7 Nov 2026, Sofia 3,000 attendees
Bulgaria's largest free and open-source software conference.
Why it is hereBest entry point into the Bulgarian and wider Balkan open-source community.
7Rank
Devtools, testing and CI 14 Sep 2026, Oslo 2,500 attendees
The Norwegian edition of the NDC developer-conference franchise, covering the .NET and web ecosystem.
Why it is hereThe strongest Nordic developer audience on the circuit.
8Rank
Devtools 24 Sep 2026, Cluj-Napoca 2,500 attendees
Romania's leading developer conference, held in the country's tech hub of Cluj-Napoca.
Why it is hereBest entry point into Romania's large and fast-growing developer workforce.
Twenty further Tier B shows qualify beyond this list, spanning DEV.BG All in One (Sofia), DUMP Days (Split), Craft Conference (Budapest) and a long tail of national developer meetups – the deepest and most evenly distributed circuit of any vertical launched so far.
Which is the biggest developer conference in Europe?
FOSDEM in Brussels, at 8,000 attendees – Europe's largest free and open-source software conference, and free to attend.
Why does this vertical have so many events compared to others?
Developer conferences are typically national or regional rather than pan-European, so the circuit is wide rather than dominated by one or two mega-shows.