Free Online Key Finder — Detect the Musical Key & Scale of Any Song
SnipSound's key finder analyzes any audio file and tells you its musical key and scale (major or minor). It supports MP3, WAV, OGG, FLAC, AAC, and M4A. The full analysis runs locally in your browser using the Web Audio API and a chroma-vector matching algorithm based on Krumhansl-Schmuckler key profiles — nothing is uploaded anywhere.
How It Works
The detector extracts a chroma vector (the energy in each of the 12 pitch classes) from your audio, then compares it against reference profiles for all 24 keys (12 major + 12 minor). The best match becomes the detected key, and you see a confidence score plus the top three candidates so you can sanity-check the result. Songs that modulate or have heavy effects may return mixed results — the alternative candidates help in that case.
Why You Need a Key Finder
Common uses: matching the key of a backing track when adding vocals or a new instrument, harmonic mixing for DJ sets (Camelot Wheel / circle of fifths), finding songs that work in the same key as your project, transposing samples to fit a song, or learning a tune by ear once you know its key.
Frequently Asked Questions
A key finder analyzes audio to determine the musical key (e.g., C Major or A Minor) of a song or recording. It uses signal processing techniques to identify which notes are most prominent and matches them against known key profiles. This is useful for DJs, producers, and musicians who need to mix tracks harmonically or transpose music.
Our key finder uses the Krumhansl-Schmuckler algorithm, a well-established method in music information retrieval. It works by: (1) converting the audio into a chromagram, which measures the strength of each of the 12 pitch classes (C through B); (2) comparing this pitch profile against known major and minor key profiles using Pearson correlation; (3) selecting the key with the highest correlation score. All processing happens locally in your browser using the Web Audio API.
The key finder supports all major audio formats including MP3, WAV, OGG, FLAC, AAC, and M4A. Any audio format supported by your web browser can be analyzed. For best results, use high-quality audio files (192kbps or higher for compressed formats).
No. All audio processing happens entirely in your browser using the Web Audio API. Your files never leave your device. This ensures complete privacy and also means the tool works offline once the page has loaded.
The Camelot Wheel is a harmonic mixing system popular with DJs. It assigns a number-letter code to each musical key (e.g., 8A for A Minor, 11B for G Major). Keys that are adjacent on the wheel are harmonically compatible, making it easy to mix tracks smoothly. Our key finder shows the Camelot code alongside the detected key.
The Krumhansl-Schmuckler algorithm is one of the most reliable methods for key detection. Accuracy depends on the audio content: songs with clear tonal centers are detected with high confidence (85%+), while atonal, highly chromatic, or heavily percussive tracks may yield lower confidence scores. The confidence percentage shown helps you gauge reliability.
The Circle of Fifths is a visual representation of the relationships between the 12 tones of the chromatic scale. Moving clockwise, each key is a perfect fifth above the previous one. Adjacent keys share many common notes, making them harmonically compatible. The outer ring shows major keys and the inner ring shows their relative minor keys.
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