We have three output formats available: table, inline, and inlineJSON. There is no non-HTML representation of the table format, but it would be useful to have such a thing for debugging purposes and for any other diff-displaying (e.g. a non-table layout side-by-side diff).

The inlineJSON is soon to be available via the MediaWiki action API (T334011), and adding tableJSON to that API would also be of benefit.