Open-source alternatives to Fastjson

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

gjson is a Go JSON parser designed for schema-less reading and value extraction. It allows for the retrieval of specific data from JSON documents using dot-notation paths without requiring the definition of predefined Go structs. The library provides tools for path-based querying, including the use of wildcards and index-based queries to locate data within objects and arrays. It also functions as a JSON lines processor, treating multi-line documents as arrays to iterate and query individual entries. Additional capabilities include converting JSON values into native Go types such as strings,

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

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

simdjson is a high-performance, header-only C++ library designed for parsing, querying, and serializing JSON data with minimal memory overhead. It functions as a hardware-aware data processing engine that leverages vector instructions to achieve gigabyte-per-second parsing speeds. By detecting host processor capabilities at runtime, the library automatically selects the most efficient instruction sets to accelerate structural analysis and validation. The library distinguishes itself through a focus on extreme efficiency and resource management. It utilizes memory mapping and padded buffer ali

UltraJSON is a high-performance JSON library and parser written in C with bindings for Python. It provides a fast alternative to standard JSON processing for decoding JSON strings into native data structures and encoding data structures back into JSON strings. The library utilizes a C-based engine to reduce processing latency and increase throughput for JSON generation and parsing. It is designed to accelerate data pipelines and optimize the handling of JSON payloads.

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

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

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

simdjson is a high-performance JSON parser that utilizes SIMD instructions to process gigabytes of data per second. It functions as a SIMD JSON parser, a multithreaded NDJSON processing library, a UTF-8 validation engine, and a tool for JSON minification and string building. The project focuses on high-throughput data processing, enabling the ingestion of massive JSON volumes and the verification of UTF-8 encoding standards. It includes dedicated capabilities for constructing JSON strings with optimized memory usage and removing unnecessary whitespace from documents to reduce file size. The

Ultrajson is a high-performance Python JSON library and C-based parser designed to minimize parsing overhead. It provides a C implementation of the JSON specification to enable fast encoding and decoding of data. The project functions as a concurrent JSON processor, supporting multi-threaded serialization and deserialization to increase data throughput and prevent blocking execution. Its capabilities cover Python data serialization and high-performance JSON processing for real-time data pipelines. This includes parsing JSON data and serializing native objects into JSON strings.

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

node-fs-extra is a Node.js file system extension that provides a set of additional methods to simplify common file and directory operations. It functions as a recursive directory manager, a JSON file processor, and a file asset manipulator, extending the standard library to provide high-level utilities for managing assets on disk. The project distinguishes itself through recursive capabilities, such as duplicating or removing nested folder structures and ensuring that all missing parent directories are automatically generated when creating files or symbolic links. It also integrates a JSON se

RapidJSON is a header-only C++ library designed for high-performance parsing, generation, and manipulation of JSON data. It functions as a dual-mode engine, providing both an in-memory document object model for tree-based manipulation and a stream-based interface for event-driven processing. The library is built to minimize memory footprint and maximize execution speed, making it suitable for resource-constrained environments. The library distinguishes itself through advanced memory management and optimization techniques, including in-situ parsing that modifies input buffers directly to elimi

Gson is a Java library designed for the serialization and deserialization of objects into structured text formats. It functions as a reflection-based data mapper, inspecting class structures at runtime to automatically convert memory-resident objects into data representations and reconstruct them back into typed language objects. The library distinguishes itself through a modular type-adapter pattern that allows for custom conversion rules for complex or nested structures. It also provides robust support for production environments by generating build-time metadata and configuration rules, wh

jsmn is a lightweight JSON parser library written in C. It provides zero-copy tokenization and incremental parsing designed for use in embedded systems and memory-constrained environments. The library identifies structural JSON elements by providing offsets into the original string rather than allocating new memory for data. It uses a single-pass scanning method and requires static-buffer allocation, meaning the caller provides the memory for tokens to avoid dynamic allocation during the parsing process. The parser supports incremental streaming, allowing it to process JSON data in chunks fr

Screaming fast JSON parsing and serialization library for Android.

Newtonsoft.Json is a data processing utility for the .NET ecosystem designed to facilitate the transformation and exchange of information. It functions as a serialization library and object mapping framework, enabling the conversion of complex application objects into formatted JSON strings and the reconstruction of structured objects from raw JSON data. The library distinguishes itself through a flexible architecture that supports both strongly-typed class mapping and a dynamic object model for schema-less data manipulation. It employs reflection-based metadata mapping to automate property a

This is a JavaScript library for parsing and serializing JSON data, with a particular focus on handling objects that contain circular references. It provides a standard JSON parser that reads text and reconstructs JavaScript values without using the eval function, guarding against code injection, alongside a standard serializer that converts objects into JSON strings for data interchange. The library distinguishes itself by offering specialized encoding and decoding for cyclical object graphs. It can serialize objects with circular references by replacing repeated object paths with JSONPath s

This is a Rust serialization library for converting data structures to and from JSON strings and byte streams. It is built as a framework within the Serde ecosystem, providing both a strongly typed parser for compile-time safety and a recursive value tree for manipulating JSON data without a predefined schema. The project supports both typed and untyped processing. It can map JSON data into specific Rust types for schema conformity or parse input into a flexible, schemaless representation. It also includes macro-based utilities for the dynamic construction of JSON objects.

oboe.js is a streaming JSON parser and HTTP stream client designed for incremental data processing. It allows applications to act upon individual JSON objects as they arrive from a network request or readable stream before the entire download completes. The library functions as a JSON stream transformer, enabling the modification, filtering, and mapping of nodes on the fly. It features path-based node selection to trigger callbacks when specific patterns are matched and can terminate a network connection early once required data is found to save bandwidth. To handle datasets larger than avai

HandyJSON is a Swift JSON serialization library and data mapper. It functions as an object mapper that converts JSON data into typed Swift models and transforms Swift objects back into JSON strings for storage or transmission. The library uses reflection to automatically map JSON keys to object properties and supports custom mapping metadata to resolve naming differences between APIs and code. It provides capabilities for extracting values from deep nested paths within a JSON structure and supports the transformation of complex types such as dates and URLs. The framework handles both the des

ObjectMapper is a JSON serialization framework for Swift that maps JSON strings and dictionaries into strongly typed classes and structs. It functions as a data mapper and converter, facilitating the bidirectional transformation of data between raw JSON and Swift model objects. The library uses protocol-based mapping to associate specific JSON keys with object properties. It supports nested key extraction via dot-notation pathing and employs custom transformation classes to bridge the gap between JSON and Swift types. The framework provides capabilities for model validation during initializa

jsonparser is a Go library for parsing, extracting, and modifying JSON data by key path without requiring predefined structs or type schemas. It uses a deterministic state machine to parse JSON directly from byte slices, enabling zero-copy traversal and lazy typed value extraction. The library provides key-path-based navigation to retrieve raw bytes and typed values from nested JSON structures, supporting extraction of strings, integers, floats, and booleans. It also enables in-place value modification and deletion at specified key paths, as well as iteration over arrays and objects using cal

JsonCpp is a C++ library for parsing, manipulating, and generating JSON data. It functions as a data interchange tool that provides a JSON parser to convert formatted text into structured data and a JSON serializer to transform internal data structures back into valid JSON strings. The library features the ability to preserve non-standard JSON comments during the deserialization and serialization process, which supports the management of human-readable configuration files. The project implements a tree-based internal representation for programmatic data access and uses a builder-based config

JSONKit is an Objective-C library used for parsing, serializing, and manipulating JSON data. It functions as a JSON parser that converts text into native data structures and a serializer that transforms native objects into formatted JSON text. The library includes a gzip compression wrapper that compresses serialized JSON payloads to reduce network transfer sizes and automatically detects and decompresses gzip buffers before decoding. The toolset provides capabilities for JSON parsing and serialization, supporting customizable indentation, character escaping, and flexible comment handling.

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