BPM & Key Detector: Free Online
This free online BPM and key detector finds any track tempo and musical key in your browser — on-device audio analysis, no uploads. Start now!
Runs 100% in your browser — Detect a track's tempo and musical key with on-device audio analysis — BPM estimate and key best-guess, nothing uploaded.
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What is Bpm detector online?
BPM & Key Detector — This free online BPM and key detector finds any track tempo and musical key in your browser — on-device audio analysis, no uploads. Start now!
No AI model — classic signal processing with the Web Audio API, all on your device. The track is downmixed to mono and resampled; an onset envelope is built from spectral flux between STFT frames; tempo comes from autocorrelation of that envelope (60–200 BPM search with parabolic peak refinement, labeled ±3%); key comes from averaging a 12-bin chromagram and correlating it against Krumhansl major/minor profiles across all tonics. Nothing is uploaded; the page is explicit that BPM is an estimate and key is a best guess.
Why use this bpm detector online?
Built for bpm detector online
This free online BPM and key detector finds any track tempo and musical key in your browser — on-device audio analysis, no uploads. Start now!
Transparent & honest
No AI model — Web Audio DSP only; BPM labeled ±3% estimate, key labeled best guess.
Private by design
Everything runs in your browser. Your inputs never leave your device.
Works everywhere
Fully responsive — perfect on desktop, tablet, and mobile. No app needed.
Regularly updated
Regularly maintained and reviewed to ensure accuracy.
Free forever
No accounts, no limits, no watermarks. Use BPM & Key Detector as much as you need.
How to use BPM & Key Detector
- 1Upload an audio file (MP3, WAV, OGG — under 50 MB).
- 2The tool decodes it locally and analyzes up to 2 minutes.
- 3Read the BPM estimate (±3%) and the key best-guess.
- 4Best on music with a clear, steady beat; verify by ear for anything critical.
What can you do with BPM & Key Detector?
- Song key finder — This free online BPM and key detector finds any track tempo and musical key in your browser — on-device audio analysis, no uploads.
- Detect bpm of audio — This free online BPM and key detector finds any track tempo and musical key in your browser — on-device audio analysis, no uploads.
- Music tempo analyzer — This free online BPM and key detector finds any track tempo and musical key in your browser — on-device audio analysis, no uploads.
Good to know
- No AI model — Web Audio DSP only; BPM labeled ±3% estimate, key labeled best guess.
- Analyzes up to 2 minutes of audio; longer files are truncated.
- Best on music with a clear, steady beat; complex or rubato material degrades results.
How it works
No AI model — classic signal processing with the Web Audio API, all on your device. The track is downmixed to mono and resampled; an onset envelope is built from spectral flux between STFT frames; tempo comes from autocorrelation of that envelope (60–200 BPM search with parabolic peak refinement, labeled ±3%); key comes from averaging a 12-bin chromagram and correlating it against Krumhansl major/minor profiles across all tonics. Nothing is uploaded; the page is explicit that BPM is an estimate and key is a best guess.
Examples
Returns ~128 BPM with high confidence and the track’s key best-guess.
Returns the laid-back tempo estimate; swung or rubato timing may read less confidently.
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Frequently asked questions
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