I really like this app. I’ve had it on my phone for years and work with it almost every day. It’s well thought out and pretty extensive in it’s feature set (tuner, metronome, chord/scale/arpeggio libraries).

While I mainly use it as a metronome I love the chord finder functionality. Just select the notes of the chord you are playing on the virtual fretboard and the app will tell you the chord name(s) that it can be. This was something that I had wanted for a long time and it’s now on my phone. Super useful!