I found one (windows based) a while back, but cannot for the life of me remember the name... really liked it. It was similar to XML Notepad from MS, but for JSON. Unfortunately the name of it was NOT "JSON Notepad" which would have made it far easier to find again. :-(

Something that would also be nice, if anyone comes up with such a beast would be the ability to edit a multi-record json file... effectively each line is a single JSON, and an LF at the end of each line/record. I've used this structure a few times. Given that JSON will typically encode special characters allowing for single-line representation by default, it's worked really well, especially combined with gzip as a stream for archiving data.

If anyone knows what that program was, would love to find it again.