Viewers yes, but I need something that takes the JSON returned from an AJAX call and gives me a nice view of it. So it needs to be something I can call through an API or locally.
The Firefox plugin states:
Normally when encountering a JSON document (content type "application/json"), Firefox simply prompts you to download the view. With the JSONView extension, JSON documents are shown in the browser similar to how XML documents are shown. The document is formatted, highlighted, and arrays and objects can be collapsed. Even if the JSON document contains errors, JSONView will still show the raw text.