Nice little tool. Not entirely sure what kind of JSON it supports. For a test I simply threw a file I had laying around at it (which basically contained a data array hidden in an object, a not sooo exotic format) and it simply did not react at all, no error message or any hint to what it supports.
Looks like a first-class Mac app. Can’t wait to try it later. However, the pricing section broke when I scrolled to it on Safari 18.1 (19619.2.8.111.5, 19619) on 14.7.1. The text escaped the rounded-rect borders.