nlohmann/json is a header-only C++ library for parsing, serializing, and manipulating JSON data with an intuitive, Python-like syntax.
The library addresses the need for seamless JSON handling in C++ by providing an interface that makes JSON feel like a first-class data type through operator overloading and modern C++ features. It supports reading and writing JSON from files, creating JSON objects from literals, STL-like container access, and implicit type conversions. The tool also implements JSON Pointer, JSON Patch, and JSON Merge Patch standards for document manipulation, and can serialize to and deserialize from binary formats including BSON, CBOR, MessagePack, UBJSON, and BJData.
The library suits any C++ project requiring JSON handling without external dependencies or complex build integration. Its single-header design means you can drop it into a project with no configuration, compiler flag adjustments, or package manager setup required, though it is also available through popular package managers for those who prefer that approach. The implementation is written in vanilla C++11, making it compatible across a wide range of compiler versions and platforms.
The project maintains a balanced issue tracker with contributions from both core maintainers and external users, indicating healthy adoption without overwhelming support demands. Maintainers typically respond to new issues and pull requests within a day. Work in the issue tracker centers on bug reports, proposed fixes, and confirmed issues, reflecting a focus on stability and correctness.
