Easy Piano Tuner is a piano tuning app that will transform your Android device into a professional quality electronic tuning aid. Unlike regular chromatic tuning apps that simply tune to a pre-calculated equal temperament this app actively measures the tonal characteristics of each note and automatically calculates the ideal stretch or offset from equal temperament. In other words it creates a custom tuning for your piano with the best compromise between intervals like fifths fourths octaves and twelfths the way aural piano tuners do when fine-tuning.

There are three levels of functionality: a free (evaluation) version a paid "plus" version with basic tuning functionality and professional version with features geared towards professional piano tuners. The extra functionality is unlocked through one-time in-app purchases.

The Free version includes the following functionality:
• Tuning functionality for the mid-range of the piano only
• Automatic note detection
• Ability to measure each note on the piano to see how its current tuning compares to the ideal tuning curve (see if a piano is roughly in tune)
• Swipe in the graphing area to show a live frequency spectrum or the inharmonicity of measured notes.

Upgrading to "Plus" adds the following functionality:
• Tuning functionality for the entire piano
• Tune to frequency standards other than A=440
• Calibrate device to an external frequency source

Upgrading to Professional unlocks all features of the "Plus" version plus the following:
• The ability to save and load tuning files so a piano doesn't need to be re-measured each time it is tuned
• Pitch raise mode that calculates overpull for an initial first pass "rough" tuning (for pianos that are extremely flat)
• Access to all future features and enhancements

Upgrade costs:
Free to Plus (approximately US$25)
Free to Pro (approximately US$125)
Plus to Pro (approximately US$100)

Note about permissions: This app requires permission to access the microphone on your device and permission to read and write files.