Free JSON to C++ Converter — Instant Structs Online

Struct Name:

Use Namespace

JSON Input

C++ Output

What Is JSON to C++?

Writing C++ data models by hand from a JSON payload is tedious — especially when you're dealing with 10+ fields and nested objects. C++ has no built-in JSON support, so libraries like nlohmann/json or RapidJSON are the standard approach. This tool generates C++ structs and classes from your JSON in seconds. The JSON specification on json.org defines the format. See cppreference.com for C++ type documentation. Also see RFC 8259 for the JSON standard.

Conversion runs in your browser. Set the struct name and optionally a namespace in the config panel. Nothing is sent to a server. The generated types work with C++11 and later. For plain C, use JSON to C.

How to Use This Tool

Paste or Upload JSON

Paste your JSON or upload a file. Set the struct name and optionally a namespace in the config panel. Invalid JSON will show an error. Use the JSON Validator to check syntax first.

Review the C++ Output

The right panel shows generated C++ structs. Add includes for nlohmann/json or RapidJSON and parsing logic as needed. Arrays become std::vector or similar containers.

Copy or Download

Use Copy or Download. For formatting JSON first, use the JSON Formatter. For validation, use the JSON Validator.

JSON to C++ Examples

Here is an example of generating C++ structs from a JSON object.

Example: Subscriber record

JSON input:

Input

Generated C++ output:

Output

When JSON to C++ Helps

When building C++ applications, game engines, or embedded systems that consume REST APIs or config files, you need typed structures for the JSON. Pasting a sample here gives you C++ structs and classes you can use with nlohmann/json or RapidJSON. Manually writing types for complex nested JSON is tedious; this tool infers the structure from your sample. For pulling out specific values first, use jq.

Frequently Asked Questions

Which JSON library should I use?

nlohmann/json is header-only and easy to integrate. RapidJSON is faster for large payloads. Both are widely used. nlohmann/json has a simpler API; RapidJSON is better for performance-critical parsing.

Does it support nested objects?

Yes. Nested JSON objects become nested structs. Arrays become std::vector or similar containers. The generator supports arbitrary nesting depth.

Is my data private?

Yes. Generation runs entirely in your browser. No JSON or code is sent to any server.

C++11 or C++17?

The generated code uses standard C++ features. std::vector and std::string work with C++11. nlohmann/json supports C++11 and later. For optional, use std::optional (C++17) or a library.

Can I use with Qt or Unreal?

Yes. The generated structs are plain C++. Qt has QJsonDocument; Unreal has its own JSON handling. You can adapt the generated types or use them as-is with nlohmann/json.

Free JSON to C++ Converter Online