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Drop an MP3, WAV or other audio file onto the tool. Your browser decodes it, then the tool tracks note onsets to estimate the tempo and compares the song’s pitch content with standard major and minor key profiles. Each result comes with a confidence rating, plus the half-time and double-time alternatives and the next most likely key. Everything runs on your device; the file is never uploaded.
Automatic detection is a starting point, not the final word. Use the tap button to confirm the tempo by ear, and check the key against a piano or your DAW.
It looks for the moments where new notes and drum hits start, then measures the most regular spacing between them. That spacing, converted to beats per minute, is the tempo estimate. Songs with clear drums give the most reliable results.
A beat at 70 BPM and one at 140 BPM line up with the same drum hits, so detectors often pick the wrong one. The tool always shows both alternatives; pick the one that matches how the song feels, or tap along to check.
It’s about 62% exact, about 90% including closely related keys, on our generated test tracks. Most misses were the relative key, for example C major instead of A minor, which share the same notes. Treat it as a strong hint and confirm by ear.
No. The file is read and decoded by your browser and analysed with JavaScript on your device. Nothing is sent to a server, so it also works with unreleased tracks.
Any format your browser can decode. MP3, WAV and AAC/M4A work almost everywhere, while OGG and FLAC depend on the browser. Use at least 5 seconds of music; the tool analyses up to 90 seconds from the middle of the track.