A free app for Android, by Grain Apps.

Harmonic Tuner is an app that will allow you to tune your instrument using the principles of harmonic tuning. This tuning method is based on the idea that every string of a guitar or bass has its own characteristic tone, and that these tones are not just a single frequency but a series of overlapping frequencies. The idea is that each note has its own frequency, and that the note is not just a single frequency but a combination of several different frequencies.

Harmonic Tuner is not just a tool for musicians and DJs but a tool for music producers as well. This tool can be used to test the intonation of a song or to tune a song to a specific key.

This app will allow you to tune your guitar using the principles of harmonic tuning.