If you produce, remix, or sample, you spend a surprising amount of time answering one question: what tempo and key is this in? Below is the workflow we use, what it gets right, and where it still needs your ear.
1. Drop the file in the browser
Open the Key & BPM Finder, drag in a WAV or MP3, and let it analyze. Everything runs locally — no upload, no waiting on a queue, no account required.
2. Trust the BPM, double-check the key
Tempo detection is robust on modern productions because it tracks onset energy across the whole file. Key detection is good but not perfect — if a song borrows from the relative minor a lot, the algorithm sometimes returns that relative key. Always cross-check by playing the I chord against the recording.
3. Use the confidence score
Each result ships with a confidence score. Below 0.6, treat it as a hint and play along on a piano. Above 0.8, you're almost certainly right and can move on.
Common gotchas
- Ballads at half-time can read as half their actual BPM. Listen for the snare backbeat to confirm.
- Loops with strong tonic-fifth bass lines can confuse the major/minor classifier.
- Live recordings drift; the detector returns the dominant tempo, not a beatgrid.