Backend Night Ljubljana

An evening for people who build and run backend systems.
On 17 September, we’re meeting at the Celtra office in Ljubljana for two backend focused talks. We’ll talk about cutting infrastructure costs, making requests faster, and the practical decisions behind systems that serve traffic at scale.

📅 Date: 17 September 2026
⏰ Time: 6:00–8:00 PM
📍 Location: Celtra office, Park Zvezda, Kongresni trg 3, 1000 Ljubljana
🎟 Admission: Free
🍕 Food and drinks: Provided after the talks

🗣️ Turning CDN capacity into faster, cheaper ad requests
Jure Mohar - Senior Software Engineer @ Celtra

Jure will explain how the team cut annual serving costs by $50,000 while making ad requests load 33% faster for end users, on average.
The key change was infrastructural. Celtra had prepaid CDN capacity on AWS that was going unused, so the team found a way to route ad requests through that quota.
He’ll cover why the change made sense, what had to change in the architecture, where things got tricky, and what the results looked like in production.

🗣️ Cutting Infrastructure costs with graviton
Matic Žgur - Principal Engineer @ Teads

A behind the scenes look at migrating a high traffic system to Graviton (AWS's own ARM based CPUs, built as a lower cost alternative to traditional x86 chips) instances as part of a broader cost cutting effort. The talk covers the architecture decisions, the tradeoffs along the way, and the real before and after numbers, including compute cost reductions of on key services alongside performance improvements in production.

👥 Who should come?
Developers, engineers, architects, students anyone curious about backend systems.

Expect practical conversations about infrastructure, performance, cost, and the tradeoffs that come with operating systems at scale.

All sessions will be in English 🇬🇧

See you there 👋