tunatuna

TunaTuna is an instrument tuner based on multi-harmonic phase correlation, which provides steady and precise feedback for getting your instrument exactly in tune. Tap the note that you want to tune and adjust your strings so that the animated line is flat. If it is trending up, you're sharp. If it's trending down, you're flat.

Some instruments can be hard to tune, especially those with low strings. That's because those strings often are vibrating more strongly at the harmonic frequencies than the fundamental! TunaTuna can help-- swipe right to access the preferences and enable up to four harmonics. Just tune the lowest harmonic that gives you a strong signal. You can even tune pianos-- TunaTuna lets you choose how to balance inharmonicity.

TunaTuna is free, ad-free, and collects no personal information.