Yes, I did a Google search and, at a quick glance at least, it seemed like an MS program.
OK, I've taken another look and (being a command line junkie) I'm totally confused. It offers me a download which is a .zip file and when I download it it unpacks and gives me a file called docx-converter.wdgt and I haven't a clue what to do with that.
It's an online tool. Upload your file, and they'll email you the conversion ...
Peter.