Audio tools
Chord, Key & Tempo Detection
Upload a track to detect its key, BPM, time signature and chord progression. Useful for transposing, jamming, or building backing tracks.
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Key, tempo, time signature and the chord progression appear here — plus a practice loop built from the track you just uploaded.
Questions answered
Frequently asked questions
Treat every field as an estimate, and the page says so under the results. The key comes from correlating the track's pitch-class profile against the standard Krumhansl–Schmuckler major and minor templates: it is dependable at finding the tonal centre on clearly tonal music, and its classic failure is confusing a key with its relative major or minor. Tempo is beat-tracked, so it can land on half or double the tempo you'd count. Modulating, rubato, atonal or very percussive tracks are the hard cases.
It is a rough harmonic sketch, not a transcription. Chords are matched window by window against 24 templates — twelve major triads and twelve minor ones — so sevenths, suspensions, diminished and augmented chords, slash chords and inversions all get flattened to the nearest plain triad. It is useful for finding the progression to jam over; it is not a lead sheet.
The time signature is a two-way decision between 3/4 and 4/4, made by checking which grouping gives the strongest downbeat contrast — 6/8 material comes out as 3/4, which matches how most people count it, and nothing more exotic is detected. Sections are structural boundaries estimated from the audio and are used to populate the practice loop; short tracks may not split into sections at all.
Audio or video files up to 100 MB and 30 minutes. Analysis is free — no credits — but you need to be signed in, and it is limited to 20 analyses a minute. Your upload is deleted from the server once the analysis returns. The practice loop below the results plays the file straight from your browser without re-uploading it, so you can slow a section to half speed with the pitch preserved.