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Kodee’s Kotlin Roundup: Kotlin Turns 15, Kotlin 2.4.0, and the Kotlin Toolchain

Kodee

Hi everyone! May and June brought so much Kotlin news that I needed a little extra space for this roundup. Kotlin turned 15, Kotlin 2.4.0 arrived with new capabilities for developers on every platform, and I found plenty of ways to learn, experiment, build AI agents and AI-powered applications, and explore useful Kotlin Multiplatform libraries. Here are the updates that stood out to me most.

Kodee-approved spotlight

The Kotlin Effect in real life

What happens when Kotlin’s logic goes beyond code? For Kotlin’s anniversary, familiar language ideas were brought into everyday situations – making them more concise, efficient, and fun. I had a great time watching the Kotlin Effect come to life outside the IDE.

Watch the video

Kodee vs. Friction

I’ve been busy fighting bugs in Kodee vs. Friction, a browser arcade game where I take on enemies like Boilerplate Golem and Callback Hydra with Kotlin-inspired power-ups. It’s built with Kotlin, Compose Multiplatform for web, Kotlin/Wasm, and a Ktor backend, and the source code is public so you can see how everything works. For the best experience, I recommend playing on a desktop or laptop.

Play Kodee vs. Friction

Free Kotlin learning resources

An anniversary is a good reason to learn something new. To celebrate Kotlin’s turning 15, select Kotlin courses are available for free on Hyperskill. Whether you want to strengthen your foundations or continue into mobile and backend development, these project-based resources offer a practical way to keep progressing.

Keep learning Kotlin

Kotlin 2.4.0

Kotlin 2.4.0 is here! The release stabilizes context parameters and explicit backing fields, expands standard library and platform capabilities, and brings improvements across Kotlin/JVM, Kotlin/Native, Kotlin/Wasm, Kotlin/JS, Gradle, Maven, and the compiler. I recommend checking out the full overview to find the changes that matter most for your projects.

See what’s new in Kotlin 2.4.0

Kotlin Toolchain 0.11

The Kotlin Toolchain is your unified entry point for working with Kotlin projects. With a single `kotlin` command, you can create, build, run, test, and publish projects – without complex plugin configuration. Version 0.11 is now available as the official evolution of the Amper project. I’m excited to see this simpler workflow continue to grow across JVM and multiplatform development.

Explore Kotlin Toolchain 0.11

Koog 1.0

Koog has reached 1.0, marking a major milestone for building AI agents in idiomatic Kotlin. The stable core comes with a one-year compatibility guarantee, improved interoperability, multiplatform observability, and support for reliable agent workflows across backend, mobile, and multiplatform applications.

Discover Koog 1.0

Grants for Kotlin library authors

The 2026 Kotlin Foundation Grant Program is open for developers building or maintaining open-source Kotlin libraries, tools, and frameworks. Projects that strengthen the Kotlin ecosystem – including work related to Kotlin Multiplatform, AI, and large language models – can apply for financial support. Applications close July 14, 2026.

Learn more and apply

Compose Hot Reload experiments with AI agents

Compose Hot Reload 1.2.0-beta01 continues the work on the experimental MCP server, giving AI agents more ways to interact with running Compose applications in real time. The beta adds support for autonomous build mode, log access, UI error inspection, and lifecycle controls such as restart and reset. It is still experimental, but it offers an interesting glimpse into how AI-assisted development could become more visual, interactive, and connected to the running app.

Try the experimental update

Compose Multiplatform 1.12.0-beta01

Compose Multiplatform 1.12.0-beta01 is here, bringing updates for shared UIs across platforms, including new graphics capabilities, iOS accessibility improvements, UI test behavior updates, and fixes for iOS, desktop, web, resources, and the Gradle plugin. Check out the release notes for the full list of changes and migration details.

Explore the release notes

Three Kotlin Multiplatform libraries worth exploring

I found three useful additions to explore on Klibs.io: ComposeMediaPlayer for cross-platform video playback, NSExceptionKt for better Kotlin/Native crash reporting on Apple platforms, and multiplatform-settings for storing key-value data in shared code. They solve very different problems, which is exactly what makes browsing the KMP library ecosystem so interesting.

Discover more libraries on Klibs.io

Booking.com’s Kotlin Multiplatform journey

Booking.com adopted Kotlin Multiplatform for an experimentation library, and the results exceeded the team’s expectations. Their story shows how KMP can improve cross-platform consistency while fitting into an existing product and engineering environment – without asking teams to abandon platform-specific development.

Read the Booking.com story

Where you can learn more

Build AI-powered apps with Kotlin and Spring AI
Evaluate Kotlin adoption with the enterprise playbook
Test Ktor REST APIs with the built-in test framework
Bring iOS 26 Liquid Glass to a Compose Multiplatform app
Connect shared business logic to UI with a multiplatform ViewModel
Read The Road to Name-Based Destructuring
Explore Compose Multiplatform 1.11.0
Learn about the Kotlin Notebook plugin update

YouTube highlights

Beyond LLMs: Kotlin Game AI
Introducing the New KMP Project Structure
KotlinConf’26 Keynote
Jake Wharton | KotlinConfersations’26
Dan Kim | KotlinConfersations’26
Six Years, Zero Regrets: Sony’s Kotlin Multiplatform Success Story | KotlinConfersations’26
What Nobody Told Us About KMP on iOS | KotlinConfersations’26
Migrating 25-year-old legacy code to Kotlin
A World of Kotlin – Animated Short Film (2026 KotlinConf Intro)

That’s all from me for this roundup. Happy 15th anniversary, Kotlin – and happy coding!

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KotlinConf’26 Keynote Highlights: Advances in Language Design, Tooling, AI-Driven Workflows, and Multiplatform Development

At KotlinConf’26, the JetBrains team and industry partners shared how Kotlin continues to evolve for developers at every scale.

Daria Voronina

Introducing a Security Support Policy for the Kotlin Standard Library

Starting with Kotlin 2.4, the Kotlin standard library now includes an 18-month security support policy, with security fixes backported across active release lines.

Anton Yalyshev

Built for Productivity: What the Data Finally Shows About Kotlin

A JetBrains Research study analyzing 28M development cycles found Kotlin cycles were about 15%–20% shorter than Java cycles on comparable work.

Alina Dolgikh

A New Default Project Structure for Kotlin Multiplatform

We are updating the default project structure for Kotlin Multiplatform projects to give modules clearer responsibilities. Read on for all the details.

Márton Braun