Key & BPM Finder — Detect Tempo And Musical Key In One Click
The ultimate prep tool for DJs, producers, and remixers. Drop any song and instantly see its musical key and BPM, with confidence scores for both. 100% browser-based.
Drop an audio file here or click to browse
MP3, WAV, FLAC, OGG, M4A, WebM
Key features
Discover what makes this tool powerful — and private.
Simultaneous Key + BPM Analysis
One pass over your audio: FFT-based chroma for the musical key, an onset-envelope autocorrelation for the tempo. Your Key & BPM show up together, ready to log into your DJ library or DAW session notes.
Harmonic Mixing Ready
We display results in both standard notation (C minor / 124 BPM) and Camelot-friendly context so you can fold the metadata into any harmonic-mixing workflow — Rekordbox, Engine DJ, Serato, Traktor, or good-old-fashioned spreadsheets.
Confidence Scores For Every Result
Both analyses return a confidence metric. Low BPM confidence? Probably a rubato track. Close major/minor correlations? Possibly a modal tune. The detector is honest about uncertainty instead of silently picking one.
Private And Free
Everything runs in your browser. Files never leave your machine. Unlimited use, no login, no credit card.
Frequently asked questions
Everything you need to know about this tool.
We build a chroma vector from overlapping FFT windows, then correlate it against the 24 Krumhansl–Schmuckler key profiles. The highest-correlation profile wins.
We build a spectral-flux-style onset envelope, autocorrelate it, and pick the lag with the strongest periodic peak inside the 50–220 BPM range. The BPM is 60 × fs_envelope / lag.
Yes, that's a known property of autocorrelation on drum-driven music. If the reported BPM feels wrong, try halving / doubling it — the detector often locks onto a sub-multiple of the true tempo.
No. The Key & BPM Finder runs 100% locally in your browser tab. Nothing is sent to our servers.
Yes on most modern phones. Analysis is CPU-intensive, so short clips will feel snappier than 10-minute extended mixes on low-end hardware.
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