Chord Detector
Estimate chord sequences from a clip using chroma analysis — fully local in the browser.
Drop a file here or browse
MP3, WAV, FLAC, M4A, OGG — up to 200 MB; analyzes the first 3 minutes locally
Select a block to hear the chord. Color shows the root note; brightness reflects confidence.
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 — the file is never uploaded for analysis.
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.
You can choose a segment size (0.25s, 0.5s, or 1s). Shorter windows follow rapid changes more closely; longer windows smooth out noise and favor steadier labels. The timeline, progression list, and top chords view help you scan the estimate quickly and copy a progression for practice, production, or DJ notes.
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.
Treat the output as a useful sketch rather than a finished transcription: complex jazz voicings, seventh-heavy progressions, and heavily processed electronic tracks often need a second pass by ear. Click a timeline block to audition the estimated chord, then refine by hand where needed.
How to use it
Load a harmonic section
Upload a clip where chords are audible.
Run detection
Start analysis to score triad templates over time.
Read the chord list
A simplified sequence of likely chords is shown.
Refine the source
Trim to a cleaner section if results look noisy.
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.
Questions about Chord Detector
01How does chord detection work?+
The audio is split into short analysis segments. For each segment the detector extracts a chroma profile and compares it with common chord templates to estimate the most likely root and chord quality. The results are then smoothed into a readable progression.
02How accurate is browser chord detection?+
Chord detection is an estimate rather than a transcription guarantee. Clear piano, guitar, vocal, and sustained harmonic material usually produces stronger results, while dense mixes, distortion, inversions, passing notes, and percussion can create ambiguous labels. Use the confidence and timeline as a guide and verify important changes by ear.
03What chords can it detect?+
The detector recognizes common major, minor, seventh, diminished, augmented, and suspended chord shapes where the available harmonic information supports them. Complex extensions or layered voicings may be simplified to the closest supported chord.
04Can I change the analysis segment size?+
Yes. Shorter segments react faster to chord changes but can be noisier. Longer segments are steadier and work well for sustained harmony. Start around 0.5 seconds, then try 0.25 seconds for quick changes or 1 second for slower progressions.
05Can I play and copy the detected progression?+
Yes. The result includes a timestamped chord timeline that can be clicked to audition a chord, plus a compact progression you can copy for arranging, practice, or transcription notes.
06Can I analyze a track from My Library?+
Yes. Open My Library in the source switcher and select a saved track. The stored audio is loaded locally into Chord Detector, so you do not need to choose the same file from your computer again.