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BPM & Key Finder
Find the tempo and musical key of songs in bulk, with tap tempo to check.
Free, no uploads, no sign-up. Runs 100% in your browser.
How BPM & Key Finder works
Each song is decoded in your browser and the first two and a half minutes are analysed in a background worker. Beats are found from changes in energy across low, mid and high bands, the tempo from how those changes repeat, and the key from a chromagram matched to major and minor profiles.
Input: MP3, WAV, FLAC, M4A, OGG. Output: CSV.
How to use BPM & Key Finder
- Drop one or more songs.
- Wait a few seconds for each result.
- Tap along to check, then download the list as CSV.
Tips
- WAV is lossless but large; MP3/AAC/OGG are compact for sharing.
- Engines load on first use and are cached afterwards.
BPM & Key Finder FAQ
- Are my files uploaded?
- No. This tool runs entirely in your browser tab. Files are read from your disk into memory and the result is generated locally.
- Is it free? Are there limits or watermarks?
- Free and open source (MIT). There are no file-size caps, daily quotas, accounts or watermarks.
- Does it work offline?
- Yes, once the page (and any engine it needs) has loaded, it keeps working without a connection thanks to the service worker cache.
Related tools
- Metronome & Click Track: Steady metronome with tap tempo, accents and subdivisions, plus a click track WAV download.
- Audio Speed and Pitch: Change speed without changing pitch, or shift pitch by semitones without changing speed.
- Audio Editor & Trimmer: Trim, fade in/out, change volume and export with a waveform.
- Volume Booster and Normalizer: Make quiet audio or video louder, or even out loudness to a standard level (EBU R128).