JSON viewer
Firefox includes a JSON viewer. If you open a JSON file in the browser, or view a remote URL with the Content-Type set to application/json, it is parsed and given syntax highlighting. Arrays and objects are shown collapsed, and you can expand them using the “+” icons.
The JSON viewer provides a search box that you can use to filter the JSON.
You can also view the raw JSON and pretty-print it.
Finally, if the document was the result of a network request, the viewer displays the request and response headers.
Console API
The JSON viewer exposes data through a console API, making it easy to access the parsed JSON and other information from the Console:
$json.data - The parsed JSON object
$json.text - The original JSON text
$json.headers - HTTP request and response headers
To access these from the console, open the Web Console, and type $json.data to explore the parsed JSON object.