This is a feature request for built in support of pretty printed rendering of JSON files (and possibly JSONP). JSON might be the most widely used "file format" for HTTP/REST based APIs. Showing them in a nicely formatted fashion would greatly enhance the developer experience for a very common use case of debugging the output of API calls. This Chrome extension implements this functionality https://chrome.google.com/extensions/detail/chklaanhfefbnpoihckbnefhakgolnmc There is an addon available for Firefox with the same name. While the extension does help a lot, it would be great to have this as part of the core experience to make it available for less sophisticated developers. Also the Chrome extension is currently implemented as a content script which only re-renders a file after it has been fully loaded which is not an ideal experience.
If the intention here is for the JSON output to be rendered nicely in the Network panel, then this is a DUP of bug 20628, which happens to be a regression of bug 27503. If the intention is to have JSON output rendered nicely in the main browser window, then the bug needs to be moved somewhere besides the "Web Inspector" component.
I meant the latter.