Parse JSON in C++

How to parse a JSON string into an object and serialize (stringify) an object back to JSON in C++. C++ has no built-in JSON; nlohmann/json is the most popular header-only library. Need to clean up the JSON first? Use the formatter & validator.

Parse JSON (string → object)

// nlohmann/json
#include <nlohmann/json.hpp>
using json = nlohmann::json;
json obj = json::parse(text);

Stringify (object → JSON string)

std::string out = obj.dump(2);

Frequently asked questions

How do I parse JSON in C++?

C++ has no built-in JSON; nlohmann/json is the most popular header-only library. Parse with the snippet above; the result is a native object/map you can read.

How do I pretty-print JSON in C++?

Use the stringify snippet above with indentation, or paste your JSON into the formatter on this page.