Antares Auto-Key Free iPhone App

It listens to music and figures out what key it’s in

The only catch is that you have to create an account on the Antares site to use it after the first few times. But we tried it and it works – within predictable limitations, for example it can only tell you the key of the moment when the music is diatonic, and it doesn’t work if you sing into it.

This is an iPhone version of the computer plug-in version that will analyze tracks. Both will then send the key data to compatible versions of Antares’ Auto-Tune program.