Key Detector
Upload a clip of a song or instrumental to get a best guess at its musical key — useful for working out what to play along with.
About this tool
Up to 240 moments spread across the whole track are analysed with a frequency transform, mixed down to mono and folded into a pitch-class profile: how much energy falls on each of the 12 notes, whatever the octave. That profile is compared with the Krumhansl-Schmuckler key profiles, well-established patterns for how strongly each note belongs to each major and minor key.
The result comes with a confidence rating and a second guess. Very often the second guess is the relative key (A minor and C major share all their notes), and the difference comes down to which note feels like home. Songs that change key, or are mostly drums, give lower confidence.