In Normal mode you can define chords and the app shows them to you. In reverse mode you can define chords on the fretboard and fretter gives you the name for the chord. This does not funktion always. For example 2400 gives you no name.
There is a free version available, so just try it. They say the free version is only limited in chord recognition, so bouzouki must be available.
developer site: http://fretterapp.com