Kotlin Conference 2025: Main Announcements and New Language Features

Kotlin Conference 2025: Main Announcements and New Language Features

From May 14 to 16, 2025, the annual KotlinConf conference organized by JetBrains took place in Berlin. The event gathered over 2,000 participants — developers, architects, and community leaders. The main theme this year was the transformation of Kotlin from a "language for Android" into a full-fledged multiplatform ecosystem. We have compiled the most important announcements and innovations for you.

1. Kotlin Multiplatform (KMP) — Official Stable Status

The most anticipated announcement of the conference was Kotlin Multiplatform exiting the Beta stage. Starting with Kotlin version 2.1, the technology is declared stable and production-ready. KMP allows writing shared code in Kotlin for Android, iOS, web, desktop, and server platforms. JetBrains presented updated documentation, tools for working with iOS, and new project templates.

2. K2 Compiler — 40% Performance Improvement

Developers announced that the new K2 compiler is now used by default. Compared to the previous version, compilation speed has increased by 40%, and code analysis has become more accurate. Upcoming updates are expected to include support for lazy evaluation at the compiler level and improved incremental builds. For IntelliJ IDEA and Android Studio users, the update will be available automatically.

3. Kotlin for Server-Side Development: New Libraries

JetBrains announced the release of Ktor 3.0 — a completely redesigned framework for creating REST APIs and microservices. Key improvements include:

• Built-in support for WebSockets and Server-Sent Events;
• Integration with Kotlin Coroutines for asynchronous request processing;
• Built-in support for OpenAPI and Swagger.

Also presented was the Exposed 2.0 library for working with databases — it now supports type-based migrations and automatic SQL query generation.

4. Artificial Intelligence and Kotlin

A separate track of the conference was dedicated to using Kotlin in AI/ML. JetBrains presented an early version of KotlinDL 2.0 — a deep learning library that now supports ONNX Runtime and allows running neural network models on mobile devices. Additionally, integration with LLMs (Large Language Models) was announced: developers will be able to write prompts and call models directly in Kotlin code.

5. Educational Initiatives and Community

At the conference, the launch of Kotlin Academy was announced — a free platform with interactive courses, tasks, and certification. The courses will cover all areas: from language basics to multiplatform development and AI. JetBrains also promised to increase grant support for Kotlin communities and conferences worldwide.

What Does This Mean for Developers?

Kotlin is confidently moving beyond mobile development. Thanks to stable KMP, the high-performance K2 compiler, and new libraries, the language is becoming a universal tool for creating cross-platform applications, server-side solutions, and even AI products. If you are not yet familiar with Kotlin — now is the perfect time to start. And if you already use it — update your tools and keep an eye on new JetBrains releases.