1Turn on your iTunes XML library. You do this in iTunes, going to settings -> advanced, and click "Share iTunes Library XML with other programs".
2Locate the XML file. Find your user folder, and then navigate to 'Music/iTunes/' and then upload the 'iTunes Music Library.xml' file.
Don't worry we do not save your library, or any of your data.
Your browser does the analyzing, and gives you the result.
NOTE: if you have many songs, it will take up to a minute to analyse your library. After you selected your iTunes library, please be patient.