This app uses the microphone to auto detect the pitch of the note being played. The 3 dials will rotate to show the note being played. The middle dial shows the pitch or note name. The inner dial shows the octave. The outer dial will show if the note is flat or sharp - The orange region is within 10 cents for good tuning, the green is within 5 cents for more accurate tuning.

Whilst optimised as a guitar tuner, this app can be used for tuning many other musical instruments. Frequency detection from B0 (30 Hz) up to C8 (4186 Hz).