Why Fifths exists
Fifths is a playable circle of fifths — a handy tool for beginner songwriters. Instead of memorizing which chords belong together, you can hear it: chords that sit next to each other on the circle naturally sound good together. Pick a key, wander to its neighbors, and you'll stumble into the progressions behind countless songs — no theory background required.
Inspiration
Fifths is inspired by Quinn Raymond's limited MIDI instrument “Q-Ray” — an instrument that embraces constraint, trading range for immediacy so that anyone can pick it up and make music. Fifths borrows that spirit: a single circle, every chord one press away.
It was built by Kevin Peckham @ Lightning Jar in Philadelphia.
The music theory
The circle of fifths arranges the 12 musical keys so that each step clockwise moves up a perfect fifth (C → G → D …). Keys that are adjacent on the circle share all but one of their notes, which is why moving between neighboring chords sounds smooth and “right.”
In Fifths, the outer ring holds the major chords and the inner ring holds each key's relative minor — a minor chord built from the same notes as its major partner. For any key you choose, the three chords most songs lean on (the I, IV, and V) sit side by side, with the relative minor (the vi) tucked just inside. That cluster of four wedges is a complete songwriting palette.
Holding Shift (or the 7 pad on touch devices) adds a seventh — one extra note that gives a chord tension and color. Dominant sevenths pull you clockwise around the circle toward the next key; that pull is the engine of the classic ii–V–I progression.
Open source
Fifths is open source. The code — SvelteKit, TypeScript, and the Web Audio API — lives on GitHub:
github.com/kevinpeckham/chord-player