HOCON (Human-Optimized Config Object Notation) is the configuration format used by React. It is a flexible version of JSON, optimized for humans, rather than computers. It allows the emission of most quotation marks and commas (as well as root-level braces), the use of the equals sign rather than the colon, and comments.

HOCON is a superset of JSON, which means that all JSON is also valid HOCON. You can also use something in between. For example, { "abc"=xyz }, "abc"=xyz, and abc=xyz are interpreted equivalently.

If you plan to write sizable configurations, it is recommended that you use a proper text editor with HOCON support.

Extensive documentation for HOCON may be found here.