Open-source alternatives to Gson

RapidJSON is a high-performance C++ library used for parsing and generating JSON data. It provides both document object model and stream-based interfaces to transform JSON strings into structured data and vice versa. The library includes a JSON schema validator to verify that documents conform to predefined rules and a Unicode transcoder for converting strings between UTF-8, UTF-16, and UTF-32 encodings. It also supports relaxed parsing for non-standard JSON containing comments or trailing commas. Additional capabilities cover JSON pointer navigation for locating specific values and string s

Fastjson is a Java data binding framework and serialization library designed to convert objects to JSON strings and parse JSON data into typed objects. It functions as a JSON parser and stream processor capable of transforming JSON strings into data structures. The project emphasizes high performance JSON processing and memory management, specifically through the use of a pipeline to stream oversized JSON objects and texts to prevent memory exhaustion. It provides capabilities for JSON data serialization and deserialization workflows, including custom JSON data mapping and the ability to def

This project is a high-performance JSON library for Go, serving as a replacement for the standard encoding/json package. It provides a serialization engine for encoding and decoding data structures, alongside a schemaless parser for extracting specific values from JSON blobs using paths. The library distinguishes itself through a focus on reducing CPU and memory overhead. It implements a high-performance encoder that utilizes buffer reuse and reduced float precision to increase data throughput. Broad capability areas include data serialization, high-performance JSON processing, and schema-le

Jackson is a Java data binding framework and multi-format data serializer used to translate data structures into native language objects. It functions as a JSON data binding library and a streaming parser that reads and writes data as discrete tokens to process large datasets with minimal memory. The project distinguishes itself through a bytecode serialization accelerator that replaces standard reflection with generated bytecode to increase data binding speed. It employs a module-based extensibility model to support a wide range of formats beyond JSON, including XML, YAML, CSV, TOML, and bin

This library is a header-only C++ framework designed for the serialization, parsing, and manipulation of structured data. It provides a recursive variant data model that represents arbitrary structures as native types, allowing developers to navigate, modify, and patch hierarchical data using standard pointer paths and declarative update patterns. The project distinguishes itself through its template-based architecture, which enables type-safe data structures and custom type mapping at compile time. It offers a unified interface for binary format abstraction, supporting multiple compact repre

Guava is a Java standard library extension and utility toolkit that provides optimized data structures, concurrency tools, and core extensions. It serves as a comprehensive set of helpers for Java development, focusing on reducing repetitive boilerplate logic. The project is distinguished by its specialized implementations of immutable collections, which ensure thread safety and data consistency by preventing accidental modification. It also includes a dedicated graph data structure library for modeling and traversing networks of interconnected nodes and edges, alongside advanced collection t

This library is a high-performance JSON processing tool for Java designed to handle data serialization and deserialization with minimal resource consumption. It provides a framework for transforming complex object graphs into JSON strings and mapping raw input directly to typed class properties. The library distinguishes itself by utilizing compile-time code generation and reflection-free mapping to eliminate expensive runtime overhead. By employing iterator-based stream parsing and zero-allocation buffer management, it processes large or deeply nested data structures while reducing garbage c

Sonic is a high-performance Go JSON serialization library that provides tools for encoding and decoding native data structures. It functions as a JIT-accelerated encoder, a JSON AST parser, a stream processor, and a lazy decoder. The project utilizes just-in-time machine code generation to optimize the encoding of large data schemas and employs a JIT assembler to maximize serialization and deserialization speeds. It features a precompiled schema warmup process to prevent latency spikes during initial execution and leverages SIMD hardware instructions for accelerated parsing. The library cove

Superjson is a lossless JSON serialization library and data transcoder. It converts complex JavaScript and TypeScript data types into strings and metadata to ensure that type identity is preserved during data transfer. The library preserves non-native types such as Dates, Maps, and Sets by splitting values into a JSON-compatible payload and a separate map of type-specific metadata. It utilizes a registry-based mapping system that allows for the definition of custom type handlers to manage third-party data types during serialization and deserialization. This utility supports cross-process dat

Ajv is a high-performance data validation framework that compiles JSON schemas into optimized, standalone JavaScript functions. By transforming declarative schema definitions into executable code, it eliminates runtime interpretation overhead and provides a secure, efficient way to enforce data integrity across both browser and server environments. The library distinguishes itself through its focus on performance and type safety. It employs advanced compilation techniques, including abstract syntax tree optimization and function caching, to ensure rapid validation. Beyond standard checks, it

orjson is a high-performance Python library for serializing and deserializing JSON data. It functions as both a JSON parsing library and a serialization engine, converting data between native Python objects and UTF-8 encoded bytes. The project provides specialized support for converting complex Python data structures, including dataclasses, datetime objects, and NumPy arrays and scalars, into JSON format. It also allows for the insertion of pre-serialized JSON blobs into documents to maintain processing speed. The library includes capabilities for memory-efficient deserialization through key

SwiftyJSON is a Swift JSON parsing library and data wrapper designed to simplify the reading and manipulation of JSON structures. It provides a toolkit for converting raw JSON strings into structured formats without requiring manual type casting or optional chaining for every value. The library focuses on simplifying nested data extraction through subscript-based value access and recursive data resolution. It ensures optional-safe value retrieval by returning default empty values instead of crashing when encountering missing keys or out-of-bounds array indices. The project includes capabilit

cJSON is a lightweight library for parsing, creating, and modifying JSON data structures within C applications. It provides a comprehensive set of utilities for transforming raw text into navigable objects, manipulating data fields within collections, and serializing complex structures into formatted or unformatted strings. The library is designed for memory-sensitive and resource-constrained environments, utilizing manual memory management and type-tagged union structures to maintain a minimal footprint. It employs recursive descent parsing and in-place string manipulation to process data ef

FlatBuffers is a cross-platform serialization library designed for performance-critical applications that require efficient, zero-copy data access. By organizing data in a structured binary format, it allows applications to read and write complex data structures directly from memory-mapped buffers without the need for intermediate parsing or temporary object allocation. The project distinguishes itself through a schema-driven approach that balances high-performance access with long-term data evolution. It utilizes a unique memory layout featuring relative offsets and inline fixed-size structu

This is a Java library and framework for creating, parsing, and validating JSON Web Tokens within Java and Android applications. It provides a comprehensive toolkit for handling signed and encrypted tokens, including the generation and verification of JWS and JWE objects. The project differentiates itself through a flexible architecture that supports pluggable JSON serialization and custom signature algorithms. It includes a dedicated key manager for generating, encoding, and organizing JSON Web Keys and key sets, as well as support for hardware security module integration. The library cover

mapstructure is a reflection-based library for the bidirectional encoding and decoding of generic map data into native typed Go structures. It functions as a tool for transforming loosely typed map values into specific structs and encoding those structs back into maps. The library utilizes Go reflection to map generic data keys to struct fields during runtime. It supports the transformation of untyped data from dynamic sources or configuration files into type-safe native structures. The mapping process includes recursive traversal of nested maps and slices, as well as the use of struct tags

yyjson is a high-performance C library for parsing, serializing, and manipulating JSON data structures. It functions as a memory-efficient data tool that utilizes custom memory pools and contiguous block allocation to minimize fragmentation and overhead. The project distinguishes itself as a SIMD JSON processor, using hardware-accelerated vector instructions for rapid string validation and parsing. It provides a toolkit for querying, modifying, and patching nested JSON objects and arrays through pointer-based access and path expressions. The library covers a broad range of data manipulation

RxJava is a reactive stream processing framework and JVM reactive extensions library. It serves as an asynchronous dataflow orchestrator used to compose event-based programs by transforming, combining, and consuming real-time data flows on the Java Virtual Machine. The project distinguishes itself through integrated backpressure flow control, which manages the emission rate between producers and consumers to prevent memory exhaustion. It further provides mechanisms for concurrent thread management and parallel data processing to offload blocking operations and maintain application responsiven

Kryo is a Java binary serialization framework and object cloning library used to convert Java objects into a compact binary format and restore them from bytes. It provides a system for creating deep or shallow copies of complex object graphs without requiring binary conversion. The project utilizes variable-length integer encoding and integer-ID class registration to reduce the size of serialized data. It handles complex object graphs through circular reference tracking to prevent data duplication and infinite loops. To maintain long-term data viability, it includes schema evolution managemen

https://github.com/json-c/json-c is the official code repository for json-c. See the wiki for release tarballs for download. API docs at http://json-c.github.io/json-c/

advanced, flexible JSON manipulation in C

faster JSON serialization for Go

Screaming fast JSON parsing and serialization library for Android.

Lightweight JSON library written in C.

picocli is a command line interface development framework and argument parser for JVM-based applications. It maps command line options and positional parameters to strongly typed Java methods and fields using a declarative, annotation-based model. The framework provides specific support for native image compilation, producing the reflection and resource configuration files necessary to build standalone binaries with reduced startup overhead. It further distinguishes itself with a dedicated system for generating shell autocompletion scripts and an ANSI terminal stylizer for applying colors and

Quarkus is a Kubernetes-native Java framework designed for building high-performance, memory-efficient applications. It utilizes ahead-of-time native compilation to transform Java code into standalone, optimized binaries that eliminate the need for a virtual machine, enabling rapid startup and reduced memory consumption. By performing code augmentation during the build phase, it shifts heavy processing tasks away from runtime, ensuring that applications are optimized for cloud-native environments. The framework distinguishes itself through a unified approach to reactive and imperative program

OkHttp is an HTTP client for the JVM and Android that enables network communication via synchronous and asynchronous requests. It provides a core identity as a comprehensive networking toolkit featuring a WebSocket client for bidirectional data synchronization, a TLS security toolkit for encrypted communication, and a programmable HTTP mock server for simulating backend responses. The project distinguishes itself through a specialized security and performance architecture. It implements mutual TLS, certificate pinning, and DNS over HTTPS to secure data in transit, while utilizing connection p