JSON to C++ Struct Converter – nlohmann/json Code

Input

Output

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Ln 1, Col 1

Convert JSON to C++ in one step

Paste JSON and get C++17 structs plus from_json and to_json functions for the popular header-only nlohmann/json library.

How to use it

Paste a JSON sample into the Input panel, open a file, or drop it onto the page. A sample is already loaded so you can see the result.
The C++ code appears instantly in the Output panel and updates as you type.
Rename the top-level type under Settings → Root type name, and use Sort keys to order fields alphabetically.
Copy the code or Download it as Root.hpp.

What the C++ generator produces

Plain structs with std::string, int64_t, double, bool and std::vector.
std::optional for values that can be missing or null.
Explicit from_json / to_json that use the original JSON keys, so any key works.
Types are declared in dependency order in a single header.

Using the generated C++ code

Parse with nlohmann/json:

#include "root.hpp"

auto j = nlohmann::json::parse(text);
Root data = j.get<Root>();
std::cout << data.users[0].name << "\n";

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JSON to C++ FAQ

Which C++ standard is required?

C++17, for std::optional. nlohmann/json 3.x finds the generated from_json and to_json functions automatically.

Is my data uploaded to a server?

No. The JSON to C++ runs entirely in your browser using JavaScript. Your data is never uploaded, logged or stored, and the tool keeps working offline after your first visit.