Written into the file
The key field gets “Am”, the comment gets “08A · Am”.
Find the key and BPM. Write them into the file.
Drop your tracks on the record and download copies with key and BPM written in. Rekordbox, Serato and Traktor read them directly.
Your files stay on your computer. Nothing is uploaded.
Drop
MP3 · FLAC
WAV · AIFF
WAV · AIFF
Tracks
| Track | Key | Classic | BPM | Status |
|---|
Output format
In Rekordbox, select the tracks, right-click and choose Reload Tag. To see 1A–12B in the key column, set Preferences → View → Key display format → Alphanumeric.
From record to library
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Drop
Drag your tracks onto the record, or choose files or a folder.
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Analyze
Key and BPM are found inside your browser and show up in the list.
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Download
Download the tagged copies; add them to your library or replace the old files.
Tag, match, convert
Compatible keys, one click
Click a slice of the record: compatible keys light up and the list filters to match.
FLAC, WAV, AIFF, MP3
Audio stays bit-identical between FLAC, WAV and AIFF. Tags and cover art come along.
Your files never leave your computer
The analysis and conversion code loads with the page and does the work on your machine. Files never reach a server.
Free, paid for by ads
You watch one short video ad per 50 files; analysis and conversion count separately. You start the ad, and if you close it, that step stays locked. No pop-ups, no fake download buttons.
Common questions
How do I show a track's key in Rekordbox?
Import the files CrateKeys gives you. For tracks already in your library, select them, right-click and choose Reload Tag. To see 1A–12B, go to Preferences → View → Key display format → Alphanumeric.
Are my files uploaded anywhere?
No. Analysis, tagging and conversion all happen in your browser, on your computer. Your files are never sent to a server, and there's no account to create.
How accurate is the key and BPM detection?
We compared our results with those of the open-source Essentia library on a 390-track archive; the agreement rates are below. No automatic analysis is 100% right, so trust your ears for important transitions.
Key · exact74%
Key · incl. compatible84%
BPM · exact89%
BPM · incl. half/double94%
Which audio formats does CrateKeys support?
Drop MP3, FLAC, WAV, AIFF or M4A. Conversion runs between FLAC, WAV, AIFF and MP3 (320 kbps), carrying over title, artist, cover art and any existing key tag. Only analysis adds a key.
Does converting MP3 to FLAC or WAV improve quality?
No. What the MP3 threw away can't be brought back; the file just gets bigger. Between FLAC, WAV and AIFF the audio stays bit-identical. We'd rather say it plainly.
Is CrateKeys really free? Why do I watch ads?
It's free, with no account. Ads pay for it: key analysis and conversion each ask for one short video ad per 50 files. You start the ad, and if you close it, that step stays locked.