How It Works
Accurate Analysis,
Zero Uploads
AUDIOTOOLZ uses Essentia.js — a WebAssembly port of the Music Technology Group's professional audio analysis library — to detect BPM and key directly in your browser. The same technology powers research labs and professional music tools worldwide. Your track is never sent to any server; it stays entirely on your device.
BPM is detected using RhythmExtractor2013, Essentia's beat-tracking algorithm that combines multiple periodicity functions for high accuracy across a wide range of genres. Key detection uses Key (Temperley profile), a research-grade tonal analysis algorithm that outperforms simple chroma correlation on real music.
Professional BPM Detection
Essentia's RhythmExtractor2013 combines onset detection, energy bands, and spectral difference to accurately estimate tempo across EDM, hip-hop, jazz, and live recordings.
Research-Grade Key Detection
Uses the Temperley tonal profile — one of the most cited key-finding algorithms in music information retrieval research — for accurate results on real-world tracks.
Camelot Wheel Ready
Every detected key is instantly mapped to its Camelot Wheel position so DJs can plan harmonic mixes. Compatible keys are highlighted on the wheel directly in the results.
Completely Private
All processing runs in JavaScript inside your browser via WebAssembly. We have no technical ability to access your audio files — they never leave your device.
Reference
The Camelot Wheel
Full Key Reference
The Camelot Wheel assigns every musical key a number (1–12) and a letter — A for minor, B for major. For harmonic mixing, move one step at a time: up, down, or between A and B at the same number. Below is the complete reference used by our tool and by software such as Mixed In Key and Rekordbox.
| Camelot | Key | Type | Compatible With |
|---|
| 1A | G♯ / A♭ minor | Minor | 12A, 2A, 1B |
| 1B | B major | Major | 12B, 2B, 1A |
| 2A | D♯ / E♭ minor | Minor | 1A, 3A, 2B |
| 2B | F♯ / G♭ major | Major | 1B, 3B, 2A |
| 3A | B♭ / A♯ minor | Minor | 2A, 4A, 3B |
| 3B | D♭ / C♯ major | Major | 2B, 4B, 3A |
| 4A | F minor | Minor | 3A, 5A, 4B |
| 4B | A♭ / G♯ major | Major | 3B, 5B, 4A |
| 5A | C minor | Minor | 4A, 6A, 5B |
| 5B | E♭ / D♯ major | Major | 4B, 6B, 5A |
| 6A | G minor | Minor | 5A, 7A, 6B |
| 6B | B♭ / A♯ major | Major | 5B, 7B, 6A |
| 7A | D minor | Minor | 6A, 8A, 7B |
| 7B | F major | Major | 6B, 8B, 7A |
| 8A | A minor | Minor | 7A, 9A, 8B |
| 8B | C major | Major | 7B, 9B, 8A |
| 9A | E minor | Minor | 8A, 10A, 9B |
| 9B | G major | Major | 8B, 10B, 9A |
| 10A | B minor | Minor | 9A, 11A, 10B |
| 10B | D major | Major | 9B, 11B, 10A |
| 11A | F♯ minor | Minor | 10A, 12A, 11B |
| 11B | A major | Major | 10B, 12B, 11A |
| 12A | C♯ / D♭ minor | Minor | 11A, 1A, 12B |
| 12B | E major | Major | 11B, 1B, 12A |
FAQ
Frequently Asked
Questions
Is this tool really free?
Yes — completely free, forever. No premium plans, no usage limits, no sign-up required. The site is supported by advertising.
Are my audio files uploaded to a server?
No. Everything runs inside your browser using Essentia.js — a WebAssembly library. Your audio file never leaves your device and is never transmitted to any server. The tool works offline once the page has loaded.
What audio formats are supported?
Any format your browser can decode — typically MP3, WAV, FLAC, M4A, OGG, and AAC. Most modern browsers support all common audio formats.
How accurate is the BPM detection?
Very high for most dance music and tracks with a clear rhythmic pulse. Essentia's RhythmExtractor2013 is one of the most accurate tempo detection algorithms in the field. Results may vary for tracks with irregular tempos, live recordings, or very sparse audio.
How accurate is the key detection?
Key detection uses Essentia's implementation of the Temperley tonal profile algorithm — a research-grade method that consistently outperforms simpler chroma-based approaches on real music. Complex, atonal, or very short samples may produce less reliable results.
What is the Camelot Wheel?
The Camelot Wheel is a system developed by Mark Davis that maps all 24 musical keys onto a clock-like diagram. Adjacent positions are harmonically compatible. It is the standard system used by professional DJs worldwide and is built into software such as Mixed In Key, Rekordbox, and Serato.
Why does the page take a moment to load the analysis engine?
The first time you visit, the browser downloads Essentia.js — a WebAssembly file containing a professional audio analysis library (~5MB). This is a one-time download and is cached by your browser. Subsequent visits load instantly.