Pick a degree pattern — 1 3 5, 1 3 7, 1 4 5, anything — and the grid shows the chord that pattern makes on every scale tone of several tonalities at once, one tonality per column, sharing the same root.
So 1 3 5 in E♭ major reads E♭ · Fm · Gm · A♭ · B♭ · Cm · D°, and the column beside it shows what the same pattern does in E♭ harmonic minor. Blank rows are notes that tonality does not contain, so each column also draws the shape of its scale.
1. The degree buttons. The root is always in. In 3-note mode you pick two more, in 4-note mode three; the rest fade until you let one go. CLEAR starts over.
2. Root. Every column is built on this note and spelled from this letter, double accidentals included — E Lydian ♯9 really does contain an F𝄪. When a chord sits on a doubled note, its plain reading is underneath.
3. The columns. Each column’s name is a menu. It lists five parent scales — major, harmonic minor, melodic minor, harmonic major and Hungarian minor — and each one branches to its seven modes. Click a parent to take the scale itself, or follow the branch to a mode (on a phone, tap the parent and the modes open underneath). Add a column with +, remove one with ×, and compare whatever you like side by side.
4. The cells. Each chord is spelled with the letters of its own scale and named strictly from those letters. When a simpler enharmonic reading exists — an inversion of a plain triad, a 7th-chord shell, or a friendlier respelling of something exotic — it sits underneath in small text. A small no 5 or no 3 tag marks a shell: the symbol names the chord the notes imply, and the tag says what was left out (with no third, the name borrows the mode’s).
5. Click a cell to hear it. Every cell holding the same notes lights up across the grid — the chords the tonalities share, which is where modal interchange lives.
6. The padlock in a cell’s corner freezes that cell’s pattern. Change the buttons and everything else follows while the locked cell keeps its chord — so you can build a sheet that mixes triads, shells and 7ths. A locked cell shows its degrees in green; click the lock again to release it. Locks travel with the page’s link.
Print (⌘P) gives you the grid alone, one landscape page.
— Noel
