Free Tool
Key Finder
Drop an audio file and detect the musical key instantly. Chroma analysis with Krumhansl-Schmuckler profiles — 100% in your browser.
Drop an audio file here or click to browse
MP3, WAV, FLAC, AIFF, OGG, M4A
Decoding…
Pitch Class Distribution
How Key Detection Works
Chroma Analysis
The audio is broken into short frames and analyzed with an FFT. Each frequency bin is mapped to one of the 12 pitch classes (C, C#, D…B), building a chroma histogram showing which notes are most present.
Krumhansl-Schmuckler Profiles
The chroma histogram is compared against 24 key profiles (12 major + 12 minor) from music cognition research. The profile with the highest correlation wins. This is the same algorithm used in professional music analysis software.
Major vs Minor
Major keys sound bright and happy (C, G, D). Minor keys sound darker and more emotional (Am, Em, Dm). The algorithm detects both and shows the best match with a confidence score.
Privacy
All analysis runs entirely in your browser using the Web Audio API. Your audio file is never uploaded to any server. Close the tab and all memory is released.
Frequently Asked Questions
How accurate is browser-based key detection?
For most recorded music, accuracy is 80–90%. Complex arrangements, key changes, and heavily atonal or percussive tracks can reduce accuracy. Check the confidence score — above 70% is a reliable result.
Why does it also show BPM and LUFS?
Since the audio is already decoded, we run tempo and loudness analysis as a bonus. The BPM uses onset autocorrelation and the LUFS is a quick integrated measurement — for full loudness analysis, use the LUFS Analyzer.
What's the pitch class chart?
The bar chart shows the energy distribution across all 12 pitch classes. The highlighted bar is the detected tonic (root note of the key). A strong tonic bar with supporting scale-degree bars indicates a confident detection.
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