Question 1

Does it analyse the whole file, or just a sample?

Accepted Answer

The whole arrangement. The track is broken into overlapping windows across its full length, each analysed on its own, and the results combined with more weight given to sections carrying clear tonal information.

Question 2

How does it handle half-time or anything outside 120–130?

Accepted Answer

Tempo is measured across the full track and the result isn’t snapped to a round number. Where a groove is genuinely ambiguous (half-time, shuffled swing, 87 against 174), the plausible readings are weighed against each other.

Question 3

What about tracks that change key partway through?

Accepted Answer

The engine works segment by segment and knows when segments disagree; that disagreement drives the confidence score down. A track that genuinely modulates lands in the amber or red band, which is the honest answer.

Question 4

Does it write tags into my files?

Accepted Answer

Not yet, and it’s the biggest thing missing. You can export a CSV, or batch-rename files to 8A - 124 - Artist - Title, which most DJ software reads on import.

Question 5

Does source quality matter? 320 against lossless?

Accepted Answer

Practically no. Key lives in the bass and low mids, and the analysis is built around that register. A clean 320 returns the same answer as a FLAC. Heavy clipping or a noisy rip does hurt.

Question 6

I play vinyl rips and pitched edits. Will tuning throw it off?

Accepted Answer

That’s handled explicitly. The engine detects how far the recording sits from concert pitch and corrects for it before deciding, so a record cut slightly sharp doesn’t bleed into the neighbouring semitone.

Question 7

Where is it weakest?

Accepted Answer

Single-chord minimal, deep tech, modal techno: anything where tonality is genuinely ambiguous. Those come back amber or red rather than getting a confident guess.

Question 8

Are my unreleased promos safe?

Accepted Answer

They never leave your machine. Analysis runs in the browser; no audio is uploaded, queued or processed on a server. Only the results sync to your account, and only if you’re signed in. There is one exception, and it is one you make on purpose: if you attach a track to a post or a message, that file is uploaded, because sending it is the whole point.

Know your key.And know how sure.

Know your key.
And know how sure.