Comment by Silphendio

JSON 5 is pretty good. It just needs to make the top-level brace and all commas optional, and add proper support for multi-line strings (writing '/n/' at the end of every line doesn't count).

Allowing only valid JavaScript identifiers to be unescaped keys is also a bit quirky (You have to quote reserved keywords).

But they will never change any of that because it would break JavaScript compatibility.