Disable Firefox built-in JSON viewer first - go to about:config page and set 'devtools.jsonview.enabled' to false
Features:
- Format JSON/JSONP responses and clipboard - Select and format/encode/decode text on every page - Collapsible arrays, objects and long values - Collapse all childs with Ctrl(Command) + Click - Collapse property also on all sibling items with Alt(Option) + Click - Count items and properties in a collection - Show collection sizes - Do its best to show large (10MB+) JSON files - Do its best to show invalid JSON files - Do not sort objects with numeric keys - Do not round large numbers - "Save as..." saves the original JSON document - Select and copy a working JSON from the formatted JSON
