API references
Welcome to the Kotlin API References page. Here you'll find links to the API documentation for the official Kotlin libraries and tools.
Standard library (stdlib)
The Kotlin Standard library provides core functionality for Kotlin programming, including essential APIs such as collections, text and string processing, ranges, sequences, and more. It extends platform-specific APIs and provides a Kotlin-first API for working with them.
Test library (kotlin.test)
A multiplatform testing library that provides common testing annotations and utility functions. It supports integration with popular test frameworks on each platform and offers a unified testing experience across the Kotlin ecosystem.
Coroutines (kotlinx.coroutines)
A powerful library for asynchronous programming using Kotlin coroutines. It offers tools to support structured concurrency, asynchronous streams, synchronization primitives like mutexes and semaphores, testing, and more.
Serialization (kotlinx.serialization)
A multiplatform serialization library. It provides a type-safe, compile-time mechanism for converting Kotlin objects to and from a variety of formats such as JSON, CBOR, and Protocol Buffers.
Kotlin I/O library (kotlinx-io)
A multiplatform library for low-level I/O operations. It defines abstractions for reading from and writing to binary streams and buffers, designed to be efficient and portable across all Kotlin platforms.
Date and time (kotlinx-datetime)
A multiplatform library for calendar-based computations. It provides representations of date values and supports timezone-specific operations.
Immutable collections (kotlinx.collections.immutable)
A multiplatform library providing immutable and persistent collection interfaces and implementations. It offers efficient copy-on-write operations that share structure between versions, so updating a collection doesn't copy the whole thing.
Kotlin Gradle plugins (kotlin-gradle-plugin)
The Kotlin Gradle plugins for compiling, testing, and packaging Kotlin code. These plugins simplify JVM and multiplatform builds, manage dependencies, and integrate with IDEs and CI systems.
Ktor
A framework for building asynchronous clients and servers in connected systems using Kotlin. Ktor is designed for scalability and flexibility and is deeply integrated with coroutines for non-blocking I/O and structured concurrency.
JVM Metadata (kotlin-metadata-jvm)
A library for reading and writing Kotlin metadata stored in JVM class files. It is primarily used by tools such as annotation processors, static analyzers, and compiler plugins.
Compose Multiplatform Material3
A multiplatform library for building user interfaces with Material Design 3 components. The API reference includes a gallery of Material 3 components where you can preview the composables.