GSON

Gson is an open-source Java library from Google that provides simple means to convert Java objects to JSON and back. It is designed to handle common Java data structures, including primitive values, arrays, collections, maps, and user-defined classes, with full support for generics and nested types. Gson aims to offer straightforward object binding with minimal configuration, while also allowing customization through custom serializers, deserializers, and TypeAdapters.

Key features include reflection-based serialization and deserialization by default, support for excluding fields, and the @Expose annotation to control exposure. It provides field naming policies to map Java field names to JSON keys, options to serialize null values, pretty printing, and lenient parsing for loosely formatted JSON. Gson also includes built-in type adapters for many standard types, including dates, and offers a GsonBuilder to configure behavior. For large documents, the library includes a streaming API (JsonReader/JsonWriter) for more memory-efficient processing.

Gson is released under the Apache License 2.0 and is widely used in Java applications and Android development for straightforward JSON binding. While it emphasizes ease of use and a small footprint, it may be complemented by other libraries like Jackson or JSON-B when more advanced features or performance characteristics are required. Gson remains a popular choice for developers seeking a reliable, easy-to-integrate solution for JSON serialization and deserialization in Java.