kotlinxserialization

Kotlinx.serialization is a multiplatform serialization library for Kotlin, developed by JetBrains. It provides a uniform API for converting Kotlin data objects to and from formats such as JSON, CBOR, and Protobuf, with serializers generated at compile time rather than via reflection. It targets Kotlin/JVM, Kotlin/JS, and Kotlin/Native.

The library centers on the @Serializable annotation and a Kotlin compiler plugin that generates type-specific serializers. It supports default values, renaming fields with @SerialName, optional and nullable properties, sealed class polymorphism, and contextual or custom serializers through KSerializer implementations and SerializersModule.

Key modules include kotlinx-serialization-core and the format-specific modules such as kotlinx-serialization-json, kotlinx-serialization-protobuf, and kotlinx-serialization-cbor. In Gradle, you typically apply the Kotlin serialization plugin and declare the corresponding kotlinx-serialization dependencies.

Usage typically involves annotating data classes with @Serializable and using a Json instance to encode and decode: Json.encodeToString(user) and Json.decodeFromString<User>(json). For polymorphic types, a SerializersModule must be registered to enable correct runtime serializer resolution.

Kotlinx.serialization is designed for Kotlin Multiplatform projects and emphasizes performance by avoiding reflection. It integrates with Kotlin's type system and works with existing data classes and sealed hierarchies, providing a stable, extensible solution for serializing data across platforms.