Key Finder — Find The Musical Key Of Any Song, Free And Instant
Free, accurate, browser-based Key Finder. Upload any audio file and get the musical key — major or minor — with confidence scores. Uses FFT chroma and the Krumhansl–Schmuckler algorithm.
Drop an audio file here or click to browse
MP3, WAV, FLAC, OGG, M4A, WebM
Key features
Discover what makes this tool powerful — and private.
Key Detection In Seconds
Drop a file, wait a few seconds, read the key. That's it. The Key Finder is intentionally zero-friction for musicians who just need to know whether a song is in D minor or F major before they pick up their instrument.
All 24 Candidates, Ranked
Alongside the winning key, the Key Finder shows every major and minor candidate ranked by correlation. Useful for ambiguous or modal tracks where the top two candidates are close.
Great For Vocal Warmups And Covers
Need to figure out what key your favourite cover is in? Drop the YouTube rip into the Key Finder and match your range — no perfect pitch required.
Runs Locally, Works Offline
Once the page is loaded the Key Finder doesn't need a network connection. Handy on long flights, at venues, or in low-bandwidth rehearsal rooms.
Frequently asked questions
Everything you need to know about this tool.
The key of a song is the tonal centre and scale it primarily revolves around — e.g. C major means the melody and chords gravitate toward the C note and use the C major scale. Knowing the key makes it easy to improvise over, transpose, or sing in the right range.
Major keys usually sound brighter / happier, minor keys sound darker / sadder. Mathematically they differ in the third degree of the scale (major = whole-whole, minor = whole-half).
Relative major and minor keys share the same seven notes (C major and A minor, for example). A purely statistical detector relies on the emphasis of the tonic. If the analysed clip doesn't emphasise either tonic strongly, the detector can pick the relative key.
Yes, completely free and unlimited. No signup, no credit card, no upload limit — analysis happens inside your browser tab.
Anything your browser can decode: MP3, WAV, FLAC, OGG, M4A / AAC, WebM. Both lossy and lossless files analyse equally well.
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