A couple nights ago I started playing my violin and realized it was out of tune. I downloaded and bought a few apps but this one seemed the best. I tuned for over an hour that night, trying to make the note light but green. when they finally did light up green I was satisfied. however, this morning when my teacher came over to give me my lesson and started to tune my violin with a Snark tuner, my violin was completely out of tune. the G string was flat, the D string was a C and the A and E strings were both sharp. I do not recommend this app. it costs $5 and does not work properly at all.