Chromtuner

Most tuner apps are afterthoughts—a website hack that runs in your browser tab with enough latency to make a live performance interesting in all the wrong ways. Chromtuner says nah, and builds an actual native macOS app that sits directly on Core Audio, sees your USB interface at full sample rate, and responds in under 50 milliseconds. That's not a feature. That's the baseline.

This is a chromatic tuner that achieves ±1 cent accuracy—the kind of precision that matters when you're recording or performing live and can't afford a wobbling needle telling you you're "close enough." It runs the YIN pitch detection algorithm on your CPU, covers A0 to C8 (27.5 Hz to 4186 Hz), and includes octave-error correction for plucked strings. The LED bar mode snaps to in-tune in under 50 ms with a hard ±0.5 cent deadband that actually locks rather than hunting back and forth like some optimistic weather vane. The Peterson-style rotating strobe is there for the musicians who care about sustained intonation work—the ones who know the difference between "in tune" and "in tune."

Where Chromtuner gets interesting is in the details most tuners ignore entirely. Eight historical temperaments—Just, Pythagorean, ¼-comma Meantone, Werckmeister III, Kirnberger III, Vallotti, Young II—are built in with movable tonic for non-equal systems. That matters for classical players, early music enthusiasts, and anyone building instruments outside the twelve-tone trap. Instrument presets cover guitar (standard, Drop D, DADGAD, Open G, half-step down, 7-string), bass (4 and 5-string), violin, viola, cello, double bass, ukulele, mandolin, and banjo—plus capo support through fret 11. Reference tones let you tap any string row to hear a clean sine wave with keyboard shortcuts c through b, soft envelope, and A4 calibration honoring whatever standard you need.

It lives in your menu bar, opens a 360-pixel popover in under 200 ms, and costs six dollars ninety-nine as a one-time purchase—no subscription, no cloud account, audio never leaves your machine. For macOS 14+. This is what happens when someone who actually plays builds a tuner instead of grabbing an API and wrapping it in a website.