JSONView is a Firefox extension that helps you view JSON documents in the browser.
Normally when encountering a JSON document (content type “application/json”), Firefox simply prompts you to download the file. 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. More info in the inaugural blog post.
Once you’ve got JSONView installed, check out this example JSON file to see the extension in action!
CouchDB users and others who need to have “application/json” sent in the HTTP Accept header to serve JSON properly should set that option in JSONView’s options panel.