Kotlin is an open-source programming language developed by JetBrains. It is statically typed: the compiler checks the type of every value before the program runs. Kotlin supports both object-oriented and functional programming styles, and its type system separates values that may be null from values that may not, which makes null-pointer errors less likely.
The Kotlin compiler targets several platforms. For the JVM (Java Virtual Machine) it produces Java-compatible bytecode, and Kotlin code can call Java code and the reverse. For browsers it generates JavaScript, or WebAssembly through Kotlin/Wasm. Kotlin/Native compiles through LLVM to native code that runs without a virtual machine, for example on iOS. Kotlin is a first-class language for Android development, and Kotlin Multiplatform lets one project share code between platforms such as Android and iOS. IntelliJ IDEA and Android Studio support Kotlin out of the box, and Gradle and Maven build Kotlin projects.
Kotlin is free and developed under the Apache 2.0 license, with its source code on GitHub. The current release is 2.4.21.