To identify the key of a song by it's chords choose the chords below and see the highlighted slices on the circle of fifths to the right. This searches all 12 possible keys for the selected chords (diatonically) and returns the keys with most matches. If there is more than one key that contains the selected chords it will display all relevant keys.

Clicking any key in the circle of fifths will display all diatonic chords within that key as guitar chords for you string ticklers.