Rated 4 out of 5 stars

Great tool but it seems that it doesn't work with JSON File extension :)

This review is for a previous version of the add-on (1.4). 

@killix06

True, it's not triggered by file extensions; it's triggered by a limited number of MIME types for the JSON format. Would be nice to be able to handle file URIs, though, and scan the file extension. If any devs would like to submit a patch, I'd love to work with you.