JIntonation

JIntonation is a harmonic-table instrument for hearing the difference between tuning systems — not just reading about them.

Hold a chord, then switch between 12-tone equal temperament and just intonation with a single tap. The notes retune underneath your fingers so you can hear the beating smooth out, instantly and in context. A live readout shows each note's frequency in hertz and, in just intonation, how many cents it sits away from the equal-tempered pitch.

The notes live on a hexagonal harmonic table. Unlike a piano keyboard, the same musical interval always points the same direction: fifths run one way, major thirds another, minor thirds another. Chords become shapes you can move around the grid, and every chromatic note is always present — changing key or mode only changes what's highlighted, never what's reachable.

WHY MUSICIANS AND STUDENTS LIKE IT
• Hear tuning theory instead of memorizing it
• Compare equal temperament and just intonation on the same chord, in real time
• See exact frequencies and cents offsets as you play
• Explore intervals and chord shapes on an isomorphic layout

FEATURES
• Hexagonal harmonic-table grid with all twelve pitch classes
• Instant switching between 12-TET and fixed just intonation, even while notes are held
• Live frequency (Hz) and cents-offset readouts
• Selectable root key, mode (the seven diatonic modes), and octave
• Six synthesized tone colors, from a pure sine to a bright, harmonically rich voice
• Multitouch — play intervals and chords with up to four voices
• Touch edges and corners to sound two or three neighboring notes at once

WHO IT'S FOR
Music students and teachers exploring temperament and intonation, composers and producers curious about microtonality, and anyone who has wondered what "just intonation" actually sounds like.

JIntonation works entirely offline. There is no account, no sign-up, and no data collection.