Unison: Piano Tuner

A free, pro-grade piano tuner. No ads. No account. No paywall. Works offline. Unison does the two things other tuning apps leave to your ear: setting the 2 or 3 strings of each note beat-free, and holding accuracy in the extreme treble and bass. Every feature is free, on all 88 keys. Unisons, solved • See the live beat rate between a note's strings, to a tenth of a hertz • "Which string is out?": a 3-step mute flow names the left, middle or right string, and says if it is sharp or flat • Guidance that calms to beat-free as you pull the string in Real piano stretch • Measure inharmonicity on a few notes; Unison fits your whole keyboard from them • Stretch styles: 4:2, 6:3, 8:4 and 10:5 bass, 4:2, 6:3 or pure 12ths in the middle, 2:1, 4:2 or 4:1 treble • Extra bass and treble stretch, plus custom offsets per key • Choose the partial the tuner listens to on each key Check any piano in 2 minutes • Play the 8 A's or every 3rd key once • Get the average offset, the bad notes, and if a pitch raise is needed • Share the result card as an image Pitch raise that respects the piano • Pre-measure the piano, then the tuner aims each key sharp by its overpull • Bass bridge, wound-string and strut breaks, with safety caps per section • Or keep the piano at its current pitch with a new A4 Everything a pro expects • Needle or strobe display, with one ring per partial • Zoomed spectrum to see each string's peak • Reference tone: hear any key's target as a sine or a piano-like tone, or A4 440 Hz • Stability check: finds a pin that is not set before you move on • Safe-turn guard warns about the wrong pin or the wrong direction • Equal plus 7 historical temperaments, and your own custom temperaments • Adjustable A4 (415 to 466 Hz), calibration check with a fork or a tone • Auto-advance through the keys in 3 orders • One file per piano with tuning history. Import and export TuneLab .tun files • Guided first tuning and a tool guide for beginners Private by design. Audio is analyzed on your device and never recorded, stored or sent. No sign-up. No network needed. Built for full-time tuners, concert technicians and serious hobbyists. If Unison helps you, a rating on the App Store helps other tuners find it.