kotlin

Kotlin is a statically typed, cross-platform programming language developed by JetBrains. It runs on the Java Virtual Machine (JVM) and can also be compiled to JavaScript or native code, enabling multi-platform development from a single codebase.

Kotlin was announced by JetBrains in 2011, with the 1.0 release in 2016 and rapid adoption since then. The language is designed to be fully interoperable with Java, allowing developers to call Java code from Kotlin and vice versa, reuse existing Java libraries, and adopt Kotlin incrementally in large projects.

Key features include null safety through nullable types, concise syntax, type inference, and a rich standard library. Kotlin supports functional programming constructs, extension functions, data classes, sealed classes, and a robust coroutines framework for asynchronous and concurrent programming. It uses a modern, expressive syntax intended to reduce boilerplate and improve readability.

Kotlin Multiplatform enables sharing common code across platforms, while platform-specific implementations cover user interfaces and platform APIs. Kotlin/JS targets browser and Node.js, and Kotlin/Native compiles to native binaries for platforms such as iOS and Linux, avoiding the JVM when needed.

In practice, Kotlin is widely used for Android app development, receiving official support from Google since 2017. It is also used for server-side development with frameworks like Ktor and Spring, as well as for desktop, web, and cross-platform projects. Tooling is strong, centered on IntelliJ IDEA, Android Studio, and Gradle-based build systems, with broad ecosystem support.

Kotlin is open source and maintained by JetBrains and the Kotlin community, released under an open-source license.