Multiplatform programming

    Support for multiplatform programming is one of Kotlin’s key benefits. It reduces time spent writing and maintaining the same code for different platforms while retaining the flexibility and benefits of native programming.

    This is how Kotlin Multiplatform works.

    • With Kotlin Multiplatform libraries, you can reuse the multiplatform logic in common and platform-specific code. Common code can rely on a set of libraries that cover everyday tasks such as , serialization, and .
    • To interop with platforms, use platform-specific versions of Kotlin. Platform-specific versions of Kotlin (Kotlin/JVM, Kotlin/JS, Kotlin/Native) include extensions to the Kotlin language, and platform-specific libraries and tools.
    • Through these platforms you can access the platform native code (JVM, JS, and Native) and leverage all native capabilities.

    With Kotlin Multiplatform, spend less time on writing and maintaining the same code for different platforms – just share it using the mechanisms Kotlin provides:

    • . Use it for sharing the common business logic that applies to all platforms.

    • Share code among some platforms included in your project but not all. Do this when you can reuse much of the code in similar platforms.

      Hierarchical structure

    If you need to access platform-specific APIs from the shared code, use the Kotlin mechanism of .

    With this mechanism, a common source set defines an expected declaration, and platform source sets must provide the actual declaration that corresponds to the expected declaration. This works for most Kotlin declarations, such as functions, classes, interfaces, enumerations, properties, and annotations.

    See KMM features, case studies and examples

    Another scenario when code sharing may bring benefits is a connected application where the logic can be reused on both the server and the client side running in the browser. This is covered by Kotlin Multiplatform as well.

    The is suitable for building asynchronous servers and clients in connected systems.

    New to Kotlin? Visit Getting started with Kotlin.

    • Creating a KMM application shows how to create a mobile application that works on Android and iOS with the help of the . Create, run, and test your first multiplatform mobile application.

    • Building a full stack web app with Kotlin Multiplatform teaches the concepts behind building an application that targets Kotlin/JVM and Kotlin/JS by building a client-server application that makes use of shared code, serialization, and other multiplatform paradigms. It also provides a brief introduction to working with Ktor both as a server- and client-side framework.