There are myriads of JSON libraries out there, and each may even have
its reason to exist. Our class had these design goals:

Intuitive syntax. In languages such as Python, JSON feels like a first
class data type. We used all the operator magic of modern C++ to achieve
the same feeling in your code. Check out the examples below and you'll
know what I mean.

Trivial integration. Our whole code consists of a single header file
json.hpp. That's it. No library, no subproject, no dependencies, no
complex build system. The class is written in vanilla C++11. All in all,
everything should require no adjustment of your compiler flags or
project settings.

Serious testing. Our class is heavily unit-tested and covers 100% of the
code, including all exceptional behavior. Furthermore, we checked with
Valgrind and the Clang Sanitizers that there are no memory leaks. Google
OSS-Fuzz additionally runs fuzz tests against all parsers 24/7,
effectively executing billions of tests so far. To maintain high
quality, the project is following the Core Infrastructure Initiative
(CII) best practices.

Other aspects were not so important to us:

Memory efficiency. Each JSON object has an overhead of one pointer (the
maximal size of a union) and one enumeration element (1 byte). The
default generalization uses the following C++ data types: std::string
for strings, int64_t, uint64_t or double for numbers, std::map for
objects, std::vector for arrays, and bool for Booleans. However, you can
template the generalized class basic_json to your needs.

Speed. There are certainly faster JSON libraries out there. However, if
your goal is to speed up your development by adding JSON support with a
single header, then this library is the way to go. If you know how to
use a std::vector or std::map, you are already set.