Answers before you analyze
Tempo & Key Finder FAQ
Straight answers about browser-local analysis, supported files, privacy and practical limits.
- Files stay on device
- Six accepted formats
- Best-effort estimates
What should I know before using the analyzer?
Ready to check a file? Use the BPM Finder for tempo, the Key Detector for musical key, or Tap Tempo when you can hear the beat but do not have a file.
Is Tempo & Key Finder really free? Are there limits?
Yes. The current BPM, key, Camelot, Tap Tempo and music-theory tools are free, with no account, payment, usage credits or daily analysis quota. You can analyze up to 20 files per batch; each file can be up to 100 MB and 20 minutes long. Browser memory and codec support still vary by device.
Is my audio uploaded?
No. Your browser decodes and analyzes the selected file on your device. The audio, filename, decoded PCM and result are not sent to our server.
Which audio formats can I use?
The file picker accepts WAV, MP3, M4A, AAC, OGG and FLAC. Actual codec decoding varies by browser and operating system.
Can I analyze more than one song?
Yes. You can select up to 20 files at once. Each file may be up to 100 MB and 20 minutes long.
How accurate are the BPM and key results?
They are best-effort estimates. The current calibration results did not meet the project’s strict accuracy thresholds, and the blind holdout has not been run. Use the Accuracy page for the measured figures and limitations.
What is a song key finder?
A song key finder estimates a recording’s tonic and major or minor mode, then shows its Camelot code, relative key and possible alternative. Treat it as a best-effort starting point and verify the result by ear.
What is a beats-per-minute finder?
A beats-per-minute finder estimates the pulse of a local audio file and shows rounded, exact, half-time and double-time values. Results can be ambiguous when the pulse changes or the recording has prominent speech or noise.
Why does the BPM look half or double what I expected?
The same groove can be counted at different pulse levels. The result includes half-time and double-time values so you can choose the interpretation that matches the music.
What is a Camelot code?
Camelot notation maps the 24 standard major and minor keys onto a numbered wheel used as a harmonic-mixing reference. A means minor and B means major.
Why is there a possible alternative key?
The analyzer compares two harmonic profiles. If they disagree, the second result is shown as a possible alternative rather than hidden.
Does the key transposer change my audio?
No. It only calculates the destination key after an integer semitone change. It does not pitch-shift, upload or export audio.
Does the Tap Tempo calculator need a microphone?
No. Tap Tempo measures the intervals between mouse, touch or Space-key taps. It does not request microphone access or read audio.
Can I use the results for DJ mixing?
Use BPM, Camelot and related-key outputs as preparation references. Arrangement, tuning, bass movement, key changes and style still matter, so listen before mixing.
Does it work on a phone?
The file picker and tools are designed for mobile browsers. Large or long files may exceed the memory available on some devices.
Are my files or results saved?
No account, song library, database or cloud audio store is active. Results exist in the current page session and disappear when you leave or reload it.