I often found myself needing a good visual tool for diffing JSON. Most other tools provided the diff in a separate pane in the UI. This tool highlights the diffs inline.

Feature request: show the lines where there is an invalid json parse error.

Right now I'm just getting the "Invalid JSON" in the top-right corner.

EDIT: This one might be a bit of a stretch, but would it be possible to be mongodb friendly? (even though it's not technically json)

Really nice otherwise, good job.