KotlinConf 2025 Through the Eyes of Green:Code & ETN Group

KotlinConf 2025

The KotlinConf 2025 event once again confirmed that Kotlin and JetBrains are on a great path forward.
This year, more than 2,200 participants attended, including a Green:Code delegation consisting of Kamil Volf, František Novosad, Pavel Habžanský, and two colleagues from Etnetera Group focused on mobile development. The strong Czech presence was also felt thanks to other companies from the Czech Republic and the team around the Kotlin Server Squad meet-up.

Despite slight transport complications, our entire group arrived safely in Copenhagen and brought back not only inspiration but also confirmation of the right direction — and a solid dose of motivation to keep advancing the Kotlin ecosystem for our clients.

Key Highlights from the Keynote

AI, Security, and Our Next Steps

JetBrains this year talks about “AI-first tooling.”
LLMs are unpredictable; the keynote emphasized history compression and introduced Koog – a framework for building AI agents with a debugger (coming soon).

Our main takeaway: we will internally verify whether Junie and Mellum meet our security standards (on-premise version, audit logs, data retention).

Technical Gems That Caught Our Attention

• Compose Multiplatform 1.8.0 (iOS stable) – shared UI across Android/iOS/Desktop/Web; the ETN mobile team is bringing a proof-of-concept.
• Kotlin Multiplatform Plugin (KMP) – the new Gradle plugin significantly simplifies configuration of multiplatform projects; preview already in Android Studio.
• Hot Reload & Live Edit of Code – instant UI preview on Android and iOS simultaneously; shortens the dev loop.
• Kotlin × Spring Boot 4 (GA November 2025) – Milestone 2 already brings full null-safety and AOT optimizations.
• Exposed 1.0 (RC) + R2DBC – asynchronous CRUD without JDBC lock-in; an alternative to JPA.
• Gradle 8.1 (stable configuration cache; Gradle 9 preview adds further optimizations) – demos of 3× faster builds; we’re evaluating integration into dynamic agents.
• Ktor 3.1.3 – the main 3.x branch migrated to kotlinx-io; we’ll assess its applicability.
• Kotlin Notebook – interactive “runtime” programming directly inside IDEA.
• Spring AI – image generation API – unified API calls (OpenAI, Stability AI…).
• Project Valhalla & inline value types (KT-77734) – an experiment that could bring compile-time immutability guarantees.
• Coroutine debugging – hooks for context logging and new tools for asynchronous code tracing.

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Why It Was Worth It

• JetBrains is pushing forward: the language + tooling roadmap is ambitious and clear.
• AI is in production – Junie & Mellum (JetBrains’ LLM model) are no longer toys but serious tools for validation.
• Kotlin Multiplatform – Compose for iOS is stable.
• Green:Code & ETN have been part of it from the start – keeping our know-how fresh.

The conference wasn’t just about presentations; networking played an important role as well, providing the opportunity to share impressions and experiences with developers from various international companies. Hearing Czech spoken in the Bella Center was a pleasant bonus — and we were genuinely surprised by how large the Czech representation in Denmark was.

We’re already looking forward to seeing everyone again at the next Kotlin Server Squad meet-up!

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