Kotlin is a statically typed programming language that runs on the Java virtual machine and also can be compiled to JavaScript source code or use the LLVM compiler infrastructure. Its primary development is from a team of JetBrains programmers based in Saint Petersburg, Russia. While the syntax is not compatible with Java, the JVM implementation of the Kotlin standard library is designed to interoperate with Java code and is reliant on Java code from the existing Java Class Library, such as the collections framework. Kotlin uses aggressive type inference to determine the type of values and expressions for which type has been left unstated. This reduces language verbosity relative to Java, which demands often entirely redundant[citation needed] type specifications prior to version 10.

As of Android Studio 3.0 (released in October 2017), Kotlin is fully supported by Google for use with their Android operating system, and is directly included in the IDE's installation package as an alternative to the standard Java compiler. The Android Kotlin compiler lets the user choose between targeting Java 6, Java 7, or Java 8-compatible bytecode.


In July 2011, JetBrains unveiled Project Kotlin, a new language for the JVM, which had been under development for a year. JetBrains lead Dmitry Jemerov said that most languages did not have the features they were looking for, with the exception of Scala. However, he cited the slow compile time of Scala as an obvious deficiency. One of the stated goals of Kotlin is to compile as quickly as Java. In February 2012, JetBrains open sourced the project under the Apache 2 license.

The name comes from Kotlin Island, near St. Petersburg. Andrey Breslav mentioned that the team decided to name it after an island just like Java was named after the Indonesian island of Java (though the programming language Java was perhaps named after the coffee.)

JetBrains hopes that the new language will drive IntelliJ IDEA sales.

Kotlin v1.0 was released on February 15, 2016.[11] This is considered to be the first officially stable release and JetBrains has committed to long-term backwards compatibility starting with this version.

At Google I/O 2017, Google announced first-class support for Kotlin on Android.

Kotlin v1.2 was released on November 28, 2017. Sharing code between JVM and Javascript platforms feature was newly added to this release.