I'm aware of at least three JSON libraries that at least can accept comments (Gson in lenient mode, Json.NET, and json-cpp are the ones I've used personally that do)-- it's hard to convince everyone that JSON needs comments, though, and comments are of limited utility if it's not guaranteed that they'll parse everywhere.

But you really only need comments in JSON if you're doing stuff like storing configuration in JSON, and JSON's too fiddly in general to be a great config file format (too easy to do something like forget a comma; no support for types beyond object, array, (floating point) number, and string). Something more like YAML without the wonky type inference would be better, IMO.

I believe Douglas Crockforf used to make the argument that JSON is not meant for human consumption and thus shouldn't be changed to better serve humans. I personally wish hjson (https://hjson.org) were to get more traction. I prefer it over both JSON and YAML.

It was Crockford. Directly from him:

> I removed comments from JSON because I saw people were using them to hold parsing directives, a practice which would have destroyed interoperability. I know that the lack of comments makes some people sad, but it shouldn't.

https://plus.google.com/+DouglasCrockfordEsq/posts/RK8qyGVaG...

Well, then why not to allow a trailing comma in lists and objects? Computers don't care and they would even be happier, because they can then just pour array and object members with a trailing comma without concerning themselves whether this is the last member or not. (Dijkstra's train toilet problem comes to mind.) Also compare with XML, where each element is self-contained.

And why to model JSON syntax closely after JavaScript literal object syntax (which is actually more convenient, by the way) which, being taken from mainstream programming languages, naturally evolved to be written by humans in small amounts not by computers in large dumps? :)