— Free tool
BPM & Key Analyser
Tempo, key and Camelot position for any track in seconds. Everything runs in your browser — your audio is never uploaded.
Drop a track here
analysed in your browser, never uploaded
or click to browse — WAV, MP3, M4A, FLAC, OGG · multiple files welcome
— How it works
Camelot notation, in one minute
The Camelot wheel maps the 24 musical keys onto a clock face: numbers 1–12, with an inner ring (A) for minor keys and an outer ring (B) for major. F minor becomes 4A, Ab major becomes 4B. The point of the system is that it turns music theory into arithmetic — two tracks mix harmonically if their codes are adjacent.
The harmonic mixing rule
From any position, three moves are safe: one step clockwise, one step anti-clockwise, or a switch between the rings on the same number. From 4A that means 3A, 5A and 4B. Stay inside those neighbours and basslines, pads and vocals from both tracks share enough notes to sit together without clashing. The wheel above highlights exactly those neighbours for every track you analyse.
Why analysis runs in your browser
This tool uses Essentia, an open-source audio analysis library built at the Music Technology Group in Barcelona, compiled to WebAssembly so it runs at near-native speed inside the page. That design choice does two things at once. It makes the tool fast — a five-minute track analyses in a few seconds because there is no upload and no queue. And it makes the privacy answer simple: unreleased dubs, demos and pre-masters never leave your machine, because there is nowhere for them to go.
— FAQ
How accurate is the detection?
Tempo detection is typically within a fraction of a BPM on steadily-beated material like house, techno and drum & bass, and we cross-check the result across the track to show you a confidence level. Key detection is strong on tonal music; on atonal or heavily atmospheric material we still show the best guess but label it low confidence rather than presenting it as fact.
Are my files uploaded anywhere?
No. The analysis engine runs inside your browser using WebAssembly. Your audio never leaves your machine — there is no upload, no server-side processing, and nothing for anyone to store. That is also why results come back in seconds: there is no transfer time at all.
Which file formats work?
Whatever your browser can decode natively: WAV, MP3 and M4A/AAC work everywhere, FLAC works in all modern browsers, and OGG works in Chrome and Firefox but not Safari. If a file fails to decode you will get a clear message rather than a wrong answer.
Why does my drum & bass track show 87 BPM?
Half/double-time ambiguity is fundamental to tempo detection — a 174 BPM track has strong energy at 87 BPM too. Whenever the detected tempo is below 90 or above 160 we show both readings with a one-click toggle, so you can pick the one that matches how you count the track.
What do I do with the results?
The Copy results button puts a single line like "174 BPM · F minor · 4A" on your clipboard, using whichever BPM reading you have toggled to. Paste it wherever you keep track metadata: the comment field in Rekordbox, Serato, Traktor or Engine DJ (the traditional home of Camelot codes for harmonic mixing), file tags via a tag editor, your crate-planning spreadsheet, or the notes of a demo submission to a label. The Camelot code is the part DJs use mid-set — tracks one step away on the wheel, or on the same number across rings, mix harmonically.