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Key & BPM Finder
Detect the musical key and tempo (BPM) of any song or audio file. Runs in your browser -- free, instant, no upload needed.
Upload Audio File
Drag & drop your file here, or browse
Supports MP3, WAV, FLAC, OGG, M4A. Max 50MB.file.mp3
0 MB
Analyzing audio... Detecting key and tempo from spectral data.
Analysis Results
Detected Key
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Detected BPM
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beats per minute
Duration
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Sample Rate
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Channels
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Credit Cost
Free
Key and BPM detection runs entirely in your browser. No credits required, no account needed, no data uploaded.
How It Works
- BPM: Uses onset detection and autocorrelation to find the tempo
- Key: Uses chromagram analysis of the frequency spectrum to determine the musical key
Accuracy
- BPM detection is 95%+ accurate for music with a clear beat
- Key detection is 80-90% accurate
- Complex or atonal music may produce less reliable results
Best For
Music production, DJ sets, catalog enrichment, mashup preparation, and finding compatible tracks for mixing.
Frequently Asked Questions
Our tool uses spectral analysis (via librosa) to detect the musical key and tempo of audio. It analyzes the frequency content to determine the key using chromagram analysis, and uses onset detection and autocorrelation to find the tempo (BPM).
BPM detection is typically 95%+ accurate for music with a clear beat. Key detection is 80-90% accurate and may occasionally suggest a relative key (e.g., A minor instead of C major). Complex or atonal music may produce less reliable results.
Yes, key and BPM detection is completely free with no account required and no usage limits. It uses zero credits for all users.
Upload files in MP3, WAV, FLAC, OGG, M4A, or WEBM format, up to 50MB. Higher-quality formats (WAV, FLAC) may produce slightly more accurate key and BPM detection due to less compression artifacts.
Every major key has a relative minor that shares the same notes (e.g., C major and A minor). Chromagram analysis cannot always distinguish between them because the pitch content is identical. If the detected key sounds wrong, try the relative major or minor — it is likely the correct answer.
The tool reports the dominant tempo of the track. Songs with gradual tempo changes or multiple tempo sections will return the most prominent BPM. For live recordings with natural tempo fluctuation, the reported BPM represents the average tempo.
DJs use BPM for beatmatching and key for harmonic mixing (mixing songs in compatible keys). Producers use key detection to find the right pitch for samples, and BPM to set the project tempo. Musicians use it to identify the key for learning songs by ear or improvising along.
Yes. Electronic music with a steady beat produces the most accurate BPM detection. For DJ mixes or sets with multiple tracks, the tool detects the dominant tempo of the uploaded section. Upload individual tracks rather than full mixes for best results.
Currently, the web tool processes one file at a time. For batch processing of multiple files, use our API to programmatically analyze entire music libraries. The API returns key and BPM data in JSON format for easy integration with music management software.
Yes. The tool reports both the key note (A, B, C, etc.) and the scale type (major or minor). It uses chromagram analysis to identify the tonal center and determine whether the harmonic content matches a major or minor scale pattern.
Yes. Upload audio to our key/BPM detection API endpoint. The API returns a JSON response with the detected key, scale type, BPM, and confidence scores. This is free for all API users with zero credit cost, same as the web tool.
Harmonic mixing is a DJ technique where you mix songs that are in compatible musical keys, creating smoother transitions. Key detection helps DJs identify compatible tracks using the Camelot Wheel or Circle of Fifths. Songs in the same key or adjacent keys on the Camelot Wheel blend harmonically without clashing.
Need a specific TTS workflow?
Compare providers, test voices, then run it through one brokered API.