How the BPM & Key Finder works
Our free online BPM and key finder analyzes any audio file directly in your browser using the Web Audio API. Tempo (BPM) is detected with onset and beat-tracking algorithms, while the musical key is estimated using a chroma-based pitch class analysis matched against the Krumhansl–Schmuckler key profiles, a well-established method for automatic key detection.
Why detect BPM and key?
- DJs and producers, match tracks for harmonic mixing and beatmatching.
- Remixers and beat-makers, quickly find the key of a sample before chopping it.
- Songwriters, identify the key of a reference track to write to.
Supported formats
MP3, WAV, M4A, OGG, FLAC, and AAC. Files up to 50 MB are supported.
Is it really free?
Yes, no signup, no upload, no limit. Everything runs in your browser, so your files stay on your device.