I've been trying to get back into playing guitar and I've noticed one thing: Both the App Store and Google Play are replete with guitar-tuning apps that are full of either upsells or advertisements.

"Stay Put" Clip For Acoustic, Electric and Bass, and Violin Display Rotates 360 Degrees (works for right or left-hand players) Tuner can be used on front of back of headstock, Rotates 360 Degree ...