kotlinxserializationcore

kotlinxserializationcore is the core component of the KotlinX Serialization library, which provides a framework for encoding and decoding Kotlin objects to and from various data formats such as JSON, Protobuf, CBOR, and others. It defines the primary interfaces, such as KSerializer and SerialFormat, and the basic infrastructure for serialization contexts, serializers, and serializers modules. The core module focuses on language‑agnostic reflection‑based serialization, enabling the generation of type‑safe serialization code at compile time through the @Serializable annotation.

The library uses Kotlin's Kotlin Metadata to discover class structure and leverages inline functions to achieve zero runtime overhead. It supports immutable data classes, sealed classes, and polymorphic hierarchies, and offers built‑in serializers for primitives, collections, maps, and enumeration types. The core module also contains serializers for common types like UUID and Date, as well as experimental support for handling nullable and delegate properties.

kotlinxserializationcore is distributed under the Apache License 2.0, allowing free use in both open‑source and commercial projects. It can be added to projects through Gradle or Maven by including the appropriate artifact, and the Kotlin compiler plugin automatically generates serializers for annotated classes. The module is designed for cross‑platform use, providing Ktor and libkoin integrations, and is part of the broader Kotlin Multiplatform ecosystem.

Developers typically instantiate a SerialFormat (for example, Json) and invoke encodeToString or decodeFromString methods provided by the core API. The framework also offers convenient functions for serializing to ByteArray, OutputStream, or JsonElement, and supports custom serialization modules for extending functionality with user‑defined serializers.