What Key is a key detection app that determines the musical key of a song in real time. Using the pitch detection algorithm from Pitch to Note, What Key matches the notes being played to major, minor, blues, bebop (jazz) and other scales in all keys, picking the scale and key with the best match.

What Key is a universal app that runs on iPod Touch, iPhone, and iPad.

What Key works best on music with minimal percussion tuned to A4=440 Hz.

What’s New

Version 3.6

Updated for newer devices.

Ratings and Reviews

1.8 out of 5
5 Ratings

5 Ratings

mastercheif91 ,

Dosen't work very well

It likes to grab onto whatever chord is playing at the moment rather than listing for a period of time and determining the key. It'll lock in for a few seconds, some times.

Picker Eight ,

Great App after I learned how to configure

I have owned this for a long time, and rely on it to find keys to songs I want to learn to play.
The best way to get highly precise readings on this app is to be sure your settings are configured correctly. I recommend going the settings tab and turning off all scales except "major". If you do this, most songs will pop up correctly and stay the same during the entire song.

HOWEVER, if you have an ability to hear and recognize minor keys, and you are testing a song that you suspect may be in a minor key - turn off the "major" scale and turn on the "melodic minor" scale and give it a try. Also if you know how to recognize a blues tune, you may get good results from setting the scales to "major and minor pentatonic."
If you just turn on all scales, the display is going to show multiple options at any given point during a song. It may also be worth noting that some scales are essentially the same but with a different starting place (ie G major Em) so if you have a bit of music theory to help you you will enjoy the app more.

Oldblackmagic ,

Piece of crap

Doesn’t work. And if there’s something I’m doing wrong there’s nothing to help me. Do not waste your money like I did.


Mark Carlotto
4.4 MB

Requires iOS 8.2 or later. Compatible with iPhone, iPad, and iPod touch.



Age Rating


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.

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