JustATuner

What JustATuner is

JustATuner is a free, open-source desktop tuner for musicians, combining a stroboscopic chromatic tuner with a just-intonation drone. Its tuner shows 12 wheels, one for each pitch class, with seven concentric rings per wheel. Users can set reference pitch and instrument transposition, as well as adjust cents bias for each wheel and octave bias for each ring. The drone offers root, root-plus-fifth, major-triad, and minor-triad voicings in either a pure sine or harmonic-stack sound. A live meter displays the just-intonation interval and cents difference, and marks LOCKED when it is within 5¢ of just intonation. A Lissajous display shows interference between the played note and drone, with controls for phosphor color, trace thickness, trail count, and resolution. Pitch detection uses a microphone; the maker recommends a quality microphone and strongly recommends headphones when the drone is on. The app is listed for Windows, Linux, and macOS on Apple Silicon M1, M2, M3, and M4 chips. Linux requires PortAudio, and its downloaded binary may need executable permission.