Most piano tuning apps use a chromatic tuner. Before phone apps, they were the most common device for tuning string instruments. Today, chromatic tuners are available in clip-on, pedal, microphone, and application formats.
Piano apps use game theory to make your lessons fun, engaging, and affordable. The Simply Piano app allows you to learn piano at your own pace in a structured manner. You can even use it as a supplement for your piano lessons.