Musical Instrument Tuner (MIT) is a free, portable, and easy-to-use tuner app that can tune a wide range of musical instruments, from acoustic guitars and electric pianos to orchestral strings and bass guitars.

The app can tune to the note, the frequency, the octave, and the tuning error in percent.

The app displays the note, the frequency, the octave, and the tuning error in a visual and interactive format.

You can adjust the tuning with a single tap and also set the reference note.

This makes it possible to tune a wide range of instruments to the exact pitch, even if the instrument is out of tune.