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Kotlin Programming Language

v2.2.21

- Solutions
- Multiplatform
- Server-side
- Data science
- Android
- Case studies
- Docs
- Language guide
- Multiplatform development
- API
- APIs overview
- Standard library (stdlib)
- Test library (kotlin.test)
- Coroutines (kotlinx.coroutines)
- Serialization (kotlinx.serialization)
- Kotlin I/O library (kotlinx-io)
- Date and time (kotlinx-datetime)
- JVM Metadata (kotlin-metadata-jvm)
- Kotlin Gradle plugins
- Ktor
- Compose Multiplatform Material3
- Community
- Teach
- Play
- Playground
- Koans

# Kotlin

Concise. Multiplatform. Fun.

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Developed by

##### Kotlin for Backend

Spring support, Java interop, coroutines.

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##### Kotlin for Server

Spring support, Java interop, coroutines.

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##### Kotlin for Backend

A simple way to boost your coding joy.

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##### Kotlin for Server

A simple way to boost your coding joy.

Try Now

##### Kotlin for Backend

A simple way to boost your productivity.

Try Now

##### Kotlin for Server

A simple way to boost your productivity.

Try Now

## Latest news

November 12, 2025

### Google Summer of Code 2025: What Our Contributors Built

Congrats to all GSoC 2025 contributors and mentors! This year’s projects have made a real impact on the Kotlin ecosystem and the contributions are already being integrated, used, and appreciated. Thank you all for your hard work! Let’s take a closer look at this year’s projects: IntelliJ Platform Gradle Plugin – Gradle Reporting and Parallel \[…\]

November 11, 2025

### Building AI Agents in Kotlin – Part 1: A Minimal Coding Agent

Building agents is weird. You’re not writing code that does things. You’re writing code that gives an LLM the ability to do things, and the LLM decides what to do. What is an agent? An agent is an LLM that calls your functions in a loop until it decides the task is complete. That shift \[…\]

November 5, 2025

### Growing Kotlin Adoption in Your Company

Guest post by Urs Peter, Senior Software Engineer and JetBrains-certified Kotlin Trainer. For readers who’d like a more structured way to build Kotlin skills, Urs also leads the Kotlin Upskill Program at Xebia Academy. This is the third post in The Ultimate Guide to Successfully Adopting Kotlin in a Java-Dominated Environment, a series that follows how \[…\]

October 29, 2025

### Finding Order in the Mayhem: A Novel Concurrency Testing Tool that Improved the Kotlin Compiler

If you’ve ever tried to track down a bug in concurrent programs, you know how chaotic and frustrating it can be: everything seems to work fine, then suddenly crashes, and you can’t quite pin down why – all while the bugs slip through.  To bring order to this chaos, at JetBrains Research we built LitmusKt \[…\]

Kotlin blog

Why Kotlin?

Simple

Code examples

- Simple
- Asynchronous
- Object-oriented
- Functional
- Ideal for tests
- Open in Playground

Simple

Asynchronous

Object-oriented

Functional

Ideal for tests

Open in Playground

Run

fun main() {
val name = "stranger"        // Declare your first variable
println("Hi, $name!")        // ...and use it!
print("Current count:")
for (i in 0..10) {           // Loop over a range from 0 to 10
print(" $i")
}
}

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## Kotlin in action

McDonald's leverages Kotlin Multiplatform (KMP) for their global mobile app, enabling them to build a codebase that can be shared across platforms, removing the need for codebase redundancies.Kotlin Multiplatform

AWS opted for Kotlin over Java for Amazon Quantum Ledger Database (QLDB) thanks to its expressiveness and structured concurrency. They rewrote QLDB in Kotlin, enhancing the user experience, benefiting from its development workflow, and adopting it fully for server-side development.Server-side

Philips utilizes Kotlin Multiplatform in its HealthSuite digital platform mobile SDK. With KMP, they accelerated the implementation of new features and fostered increased collaboration between Android and iOS developers.Kotlin Multiplatform

Adobe Experience Platform chose Kotlin for server-side development because of its concise syntax, async capabilities, and interoperability with Java. This shift boosted productivity and improved the developer experience, replacing Java for real-time services.Server-side

By sharing over 80% of logic across iOS and Android, Forbes now rolls out new features simultaneously on both platforms, keeping the flexibility to withhold or customize features based on the specific platform.Kotlin Multiplatform

Atlassian adopted Kotlin for the Jira Software cloud, leveraging its Java compatibility for seamless integration and minimizing migration challenges. Kotlin's ease of use improved developer productivity and boosted team satisfaction and efficiency.Server-side

See all case studies

## Share code on your terms and for different platforms

Simplify the development of cross-platform projects with Kotlin Multiplatform. It reduces time spent writing and maintaining the same code for different platforms while retaining the flexibility and benefits of native programming. Kotlin applications will work on different operating systems, such as iOS, Android, macOS, Windows, Linux, watchOS, and others.

Learn about Kotlin Multiplatform

## Kotlin + AI

JetBrains is investing in AI models tailored for Kotlin, providing open data, benchmarks, and AI-native tooling integrated into your workflow.

At the same time, Kotlin makes it easy to build your own AI-powered features with seamless backend integrations and a growing ecosystem.

### What you get with Kotlin + AI

- Strong support across JetBrains AI tools like AI Assistant and Junie
- Robust functionality for building AI-powered apps on the JVM
- Native integration with tools like Spring AI and LangChain4j
- Open data and benchmarks for better code generation

Learn about JetBrains AIBuild AI apps with Kotlin

### Build your own AI agents with Koog

Koog is JetBrains’ new Kotlin-native framework for creating powerful AI agents that run locally, interact with tools, and automate complex tasks. Whether you’re developing a simple chat assistant or an advanced multi-step workflow, Koog gives you full control with clean Kotlin code – no external services are required. Build, extend, and experiment with AI agents entirely in Kotlin.

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## Big, friendly and helpful community

Kotlin has great support and many contributors in its fast-growing global community. Enjoy the benefits of a rich ecosystem with a wide range of community libraries. Help is never far away — consult extensive community resources or ask the Kotlin team directly.

Join the community

## Kotlin Foundation

Actively supports community efforts in developing the Kotlin ecosystem.

Learn more

## Start using Kotlin today!

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Stay in touch:

- Contributing to Kotlin
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- Opt-Out

Supported and developed by JetBrains.

Kotlin™ is protected under the Kotlin Foundation
and licensed under the Apache 2 license.