JSON for Humans.

JSON is great. Until you miss that trailing comma... or want to use comments. What about multiline strings? JSONH provides a much more elegant way to write JSON that's designed for humans rather than machines.

Since JSONH is compatible with JSON, any JSONH syntax can be represented with equivalent JSON.

JsonhCpp

JsonhCpp is a parser implementation of JSONH V1 & V2 for C++.

Example

{
    // use #, // or /**/ comments
    
    // quotes are optional
    keys: without quotes,

    // commas are optional
    isn\'t: {
        that: cool? # yes
    }

    // use multiline strings
    haiku: '''
        Let me die in spring
          beneath the cherry blossoms
            while the moon is full.
        '''
    
    // compatible with JSON5
    key: 0xDEADCAFE

    // or use JSON
    "old school": 1337
}

Usage

Everything you need is contained within jsonh_reader:

#include "jsonh_cpp.hpp" // for jsonh_cpp

std::string jsonh = R"(
{
    this is: awesome
}
)";
json::object_t element = jsonh_cpp::jsonh_reader::parse_element<json::object_t>(jsonh).value();

Dependencies

• C++20
• nlohmann/json (v3.12.0 - patch 2026/02/19 22:32)
• lewissbaker/generator (patch 2026/03/03 23:26)
• martinmoene/expected-lite (v0.10.0) - backport
• catchorg/Catch2 (v3.13.0) - help
• rindeal/Amalgamate (v0.99.0)

Limitations

In comparison to JsonhCs, this C++ implementation has some limitations.

UTF-8 only

The input stream must be in UTF-8 encoding.

If using a different encoding, consider converting to UTF-8 using utfcpp.

Fixed-size numbers

There is no option to parse numbers with arbitrary range/precision. Numbers are parsed as long double, which is generally 64-bit.