Enter a NWCtxt tune in the text area or use the browse button to
upload a NWC 2.75 or NWCtxt file then press "Convert to MusicXML",
you'll be prompted to download a MusicXML file if the conversion is successful.
To get a NWCtxt file, you need Noteworthy Composer. Go to File > Save As... and choose NWC Text File.
The converter now supports NWC files as well, if they have been created with Noteworthy Composer 2.75.