Open-source alternatives to Jsoncpp

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

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

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

This is an educational tutorial that walks through implementing a complete JSON library from scratch in C. The project covers the full data lifecycle of JSON, including parsing text into structured in-memory representations, validating input against the specification, serializing data back into standard JSON output, and providing structured access to elements within parsed arrays and objects. The implementation is built around a hand-written recursive descent parser that processes JSON text by matching grammar rules to build a structured data tree. Parsed values are stored in a tagged union r

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,

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

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.

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

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

The C++ REST SDK is a library for asynchronous HTTP and RESTful communication in native C++ applications. It provides a non-blocking network client for sending requests and receiving responses, a JSON parser for serializing and deserializing data, and a WebSocket client library for real-time, full-duplex communication. The project includes a dedicated OAuth2 authentication client to manage access tokens and authorization flows for secure communication with protected cloud resources. It utilizes a task-based asynchronous model to coordinate background operations and keep application interfaces

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.

VBA-JSON is a library designed for parsing and serializing JSON data within Visual Basic for Applications environments. It functions as an office automation data library, enabling legacy Microsoft Office applications to process structured data and interact with modern web services. The tool converts raw JSON text into native objects and collections, allowing developers to access and manipulate data using standard indexing and iteration methods. It also performs the reverse operation, transforming native language structures into JSON-compliant strings for exchange with external systems. By ha

UglifyJS2 is a suite of tools designed for parsing, beautifying, mangling, and minifying JavaScript code. It functions by converting source code into an abstract syntax tree to enable programmatic analysis and transformation, and it includes a dedicated generator for creating associated source maps. The project optimizes web production builds by compressing script logic and removing unreachable code. It utilizes name mangling to shorten variable and property names and implements a beautifier to reconstruct compressed scripts into a human-readable layout. The toolset covers broad capability a

jq is a command-line JSON processor and data transformer. It provides a functional query language used to slice, filter, map, and transform structured JSON data directly within a terminal. The utility functions as a data transformer that reshapes JSON input into different structures or formats based on declarative logic. This allows for the extraction and analysis of structured data from sources such as API responses and system logs.

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

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

This project is an educational compiler implementation and architecture demo. It serves as a small-scale C-style language compiler designed to demonstrate the fundamental stages of transforming source code into executable machine instructions. The codebase functions as a tool for compiler architecture education and design prototyping. It illustrates the process of building an educational language implementation to help users understand the mechanics of parsing and code generation. The implementation covers the primary stages of a compiler pipeline, including regular expression tokenization,

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

Moshi is a JSON serialization library and parser for Kotlin and Java. It functions as a reflectionless JSON encoder that converts typed objects to JSON strings and parses JSON data back into language objects. The library distinguishes itself through compile-time adapter generation, which removes the performance overhead associated with runtime reflection. It also provides a polymorphic JSON mapper that uses type identifiers to resolve and instantiate specific subclasses of a common base type. The framework supports custom adapter definitions for specialized type conversion, including nullabi

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

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

ArduinoJson is a C++ library for parsing and manipulating JSON data and MessagePack binary streams on microcontrollers with limited memory and processing power. It provides the core primitives necessary for embedded data serialization and parsing, enabling devices to exchange structured data over serial or network interfaces. The library is distinguished by its focus on microcontroller memory management, employing strategies such as pool-based allocation, string deduplication, and non-owning string views to minimize RAM usage. It further optimizes for constrained environments by allowing cons

JSHint is a JavaScript static analysis tool and linter designed to detect errors and enforce coding standards. It functions as a syntax validator that scans source code to identify potential logic problems and programming mistakes before the code is executed. The tool provides a command line interface for analyzing files and directories. It supports the export of analysis results into standardized formats such as Checkstyle for integration with external build tools. Analysis is managed through a system of linting rule management and environment global configuration. This includes the ability

This project is a Python library and command-line tool designed to convert Markdown text and files into structured HTML fragments. It functions as a Markdown-to-HTML converter and parser that transforms piped text or source files into web-ready documents. The project is an extensible text processor featuring a pluggable API for defining custom inline and block syntax. This modular framework allows for the registration of specialized syntax extensions, such as tables and footnotes, and provides a system for managing runtime configuration settings. The conversion process covers multilingual te

This project is an educational compiler implementation and a minimalist compiler construction tutorial. It serves as a practical example of how to build a functional compiler through a simplified end-to-end development process, transforming source code into executable instructions. The implementation is designed to teach the fundamentals of language implementation and compiler design. It focuses on the essential mechanics of transforming source code by demonstrating the core architecture of a translation process. The system covers the primary stages of compilation, including lexical analysis

This project is a comprehensive sample library and implementation guide for ASP.NET Core. It provides a collection of practical examples and projects that demonstrate how to build web applications, RESTful APIs, and high-performance services. The repository focuses on a variety of architectural patterns, including the development of Minimal APIs, contract-first gRPC services, and real-time communication using WebSockets and Server-Sent Events. It includes detailed implementations for user identity and security, such as token-based authentication and CSRF protection. The codebase covers a bro