Microsoft finally added the ability to compare two workbooks in Excel 2013:<p><a href="https:&#x2F;&#x2F;support.office.com&#x2F;en-us&#x2F;article&#x2F;Basic-tasks-in-Spreadsheet-Compare-f2b20af8-a6d3-4780-8011-f15b3229f5d8" rel="nofollow">https:&#x2F;&#x2F;support.office.com&#x2F;en-us&#x2F;article&#x2F;Basic-tasks-in-Spre...</a><p>Not a command line tool, and no API, but they delivered the basic feature.  As far as I can tell, it isn&#x27;t used very much.