In the case that your JSON isn’t really JSON (JSONView is pretty strict) it’ll display an error but still show you the text of your document. The JSONView extension ( install) will parse a JSON document and display something prettier, with syntax highlighting, collapsible arrays and objects, and nice readable formatting. I’ve always wanted a Firefox extension that would give JSON the same treatment that comes built-in for XML, and after searching for it for a while I just gave up and wrote my own. If you try the same thing with an XML document, it’ll display a nice formatted result with collapsible sections. For example, if you try to visit a URL that produces JSON (using the official “application/json” MIME type), Firefox will prompt you to download the file. However, JSON hasn’t quite caught up to XML in terms of tool support.

It’s simple, lightweight, easy to produce and easy to consume.

I’m a big fan of JSON as a data exchange format. JSONView - View JSON documents in Firefox

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