Great idea - I hadn't thought of diff. I'll have to have a think about how it might fit into the UI, since there's only one input box. Any ideas on what a good input flow might look like?
Looking at it again, string diff could probably just be a new mode. Since you already have the two input boxes on the left and right of them. Somehow reusing them to work as a diff? I'll make GH issue with a possible design