# JSON for Modern C++

JSON for Modern C++ is a header-only C++11 library that turns JSON into a first-class C++ data type, using the operator magic of modern C++ so that creating, reading, and modifying JSON values feels as natural as it does in languages like Python. The whole library is available as a single header, `json.hpp`, with no dependencies, no subproject, and no complex build system to set up; a companion header, `json_fwd.hpp`, provides forward declarations to keep compile times down. See [header-only integration](https://json.nlohmann.me/integration/index.md) for details. It is heavily unit-tested with 100% code coverage, checked with Valgrind and the Clang Sanitizers for memory leaks, and continuously fuzz-tested by Google OSS-Fuzz.

## Quick start

Add the single header to your project and use the library like this:

```
#include <iostream>
#include <nlohmann/json.hpp>

using json = nlohmann::json;

int main()
{
    // parse a JSON string
    json j = json::parse(R"({"happy": true, "pi": 3.141})");

    // access and modify values
    j["name"] = "Niels";
    j["list"] = {1, 0, 2};

    // serialize with an indent of 4 spaces
    std::cout << j.dump(4) << '\n';
}
```

Get the library by copying the single header [`json.hpp`](https://github.com/nlohmann/json/releases) from the releases page into a directory `nlohmann` on your include path, or by installing it with a package manager:

```
brew install nlohmann-json    # Homebrew
vcpkg install nlohmann-json   # vcpkg
```

```
find_package(nlohmann_json 3.12.0 REQUIRED)
target_link_libraries(myproject PRIVATE nlohmann_json::nlohmann_json)
```

See [Integration](https://json.nlohmann.me/integration/index.md) for CMake in detail, all supported package managers (Conan, Meson, Bazel, Conda, and more), and pkg-config.

## Explore the documentation

- **Features**

  ______________________________________________________________________

  Creating, parsing, accessing, and serializing JSON values, JSON Pointer/Patch, binary formats, and more.

  [Features](https://json.nlohmann.me/features/index.md)

- **Integration**

  ______________________________________________________________________

  Add the library to your project via a single header, CMake, a package manager, or pkg-config.

  [Integration](https://json.nlohmann.me/integration/index.md)

- **API documentation**

  ______________________________________________________________________

  The complete reference for `basic_json` and its member functions, types, and related classes.

  [API documentation](https://json.nlohmann.me/api/basic_json/index.md)

- **FAQ**

  ______________________________________________________________________

  Answers to common questions and known surprises when using the library.

  [FAQ](https://json.nlohmann.me/home/faq/index.md)

- **Releases**

  ______________________________________________________________________

  What changed in each release, with links to the relevant documentation.

  [Releases](https://json.nlohmann.me/home/releases/index.md)

- **Community**

  ______________________________________________________________________

  The ecosystem, contribution guidelines, governance, and quality assurance around the project.

  [Community](https://json.nlohmann.me/community/index.md)

Unreleased changes

This documentation is built from the `develop` branch and may describe changes that are not part of a release yet. Their version numbers are followed by an unreleased badge; see [Releases](https://json.nlohmann.me/home/releases/index.md) for what shipped in each version.

The library is licensed under the [MIT License](https://json.nlohmann.me/home/license/index.md). The source code, issue tracker, and discussions are on [GitHub](https://github.com/nlohmann/json).