Chord Detector

What it does

Chord Detector estimates a sequence of chords from an audio clip using chroma features. Energy across the twelve pitch classes is grouped over short time windows and matched against major and minor triad templates.

Results are heuristic: clear guitar or piano progressions work better than dense mixes. Everything runs in your browser.

How chroma-based chord detection works

Every note has a pitch class — C, C♯, D, and so on — regardless of octave. By summing spectral energy into these twelve classes over a short window, the tool builds a chroma vector that reflects which notes are sounding at that moment. Comparing that vector against templates for every major and minor triad picks the closest match, and the process repeats across the clip to build a sequence.

Getting a cleaner chord read

Acoustic or clean electric guitar, piano, and simple band arrangements with sustained chords give the most reliable results. Fast strumming, heavy distortion, dense orchestration, or bass-heavy mixes blur the chroma vector and can produce noisy or jumping labels. If a section sounds off, trim to a cleaner passage first with the Audio Trimmer and try again.

Combine chord estimates with the Key Detector for a fuller harmonic picture, or check tempo first with the BPM Detector.

How to use it

Tip: A verse or chorus with a steady strumming or comping pattern usually reads more cleanly than an intro fill or a drum break, since the chroma vector has more harmonic content to work with.