Comment by bleachisback

The first C++ JSON library that appears when you google it is a single header file.

https://github.com/nlohmann/json

I know because I used it years ago in school.

One of the fastest libraries (https://github.com/miloyip/nativejson-benchmark#parsing-time) is also header-only and compares its speed to strlen.

https://github.com/Tencent/rapidjson