Free · No sign-up · Live from your mic

Live Key Detector

No file needed. Play an instrument or point your mic at whatever is playing, and the key settles in as it listens — with the Camelot code, a confidence reading and the runner-up keys.

Press start, then play some music

Audio is analysed live in your browser and never recorded, stored or uploaded.

What is a live key detector?

A live key detector finds the musical key of sound as it happens, through your microphone, instead of analysing a file after the fact. That distinction matters whenever the music doesn't exist as a file you can upload: an instrument you're sitting at, a band mid-rehearsal, a record spinning, or whatever the venue is playing.

Under the hood it builds a running chromagram — a profile of how much energy lands on each of the twelve pitch classes — and matches that profile against all 24 major and minor keys several times a second. The estimate accumulates rather than resets, which is why the key visibly settles and the confidence reading climbs the longer it listens.

Because the analysis is frame-by-frame in your browser, nothing is ever recorded: each slice of audio is analysed and immediately discarded, and only the twelve-number profile is kept in memory until you clear it.

Live key detector features

Works without a file

Microphone in, key out. Pianos, rehearsals, vinyl and room audio are all sources a file-upload key finder can't touch.

Estimate that converges

Every frame adds to the running profile, so the result stabilises as the music unfolds instead of jumping on every chord change.

Camelot code included

The detected key comes with its Camelot wheel position, so DJs can go straight from listening to planning the next record.

Confidence you can read

The confidence number is the winning key's margin over the runner-up — a low margin honestly tells you the music is ambiguous.

Runner-up keys listed

The relative major or minor is the classic near-miss, so the other leading candidates are always shown alongside the winner.

Nothing recorded, ever

Frames are analysed in the browser and thrown away instantly. No recording, no upload, no account — just the accumulated note profile.

Who uses live key detection

Musicians sitting at an instrument

You're at a piano or holding a guitar and want to know what key the thing you're playing is in. There is no file to upload — the sound only exists in the room, which is exactly the case a microphone handles.

Bands in rehearsal

Working out what key the guitarist actually settled on, without stopping the run-through to ask. The estimate accumulates while you keep playing, so nobody has to hold a chord for the tool.

DJs at a venue

A track playing on the house system that you want to follow, and no file, no ID, no time. Pointing a phone mic at it for ten seconds gets you a key and a Camelot code to plan the next record.

Worship and church musicians

Congregational songs get transposed constantly to fit whoever is leading. Detecting the key of what's actually being played beats hunting for the chart that matches this week's arrangement.

How live key detection works

1. Start listening
Allow microphone access and play. Nothing is recorded — each frame of audio is analysed and thrown away, and only the accumulated note profile is kept.
2. The profile builds up
Every frame contributes to a running chromagram — how much energy sits on each of the 12 pitch classes. Silent frames are skipped so quiet gaps don't dilute it.
3. The key converges
The accumulated profile is matched against all 24 keys several times a second. The longer it listens the more the estimate settles, which is why confidence climbs over time.

Live key detector FAQ

How is this different from the file Key Finder?

Same detection maths, different input. The Key Finder analyses an audio file you upload and gives one answer for the whole track. This page listens live through your microphone, so it works for a piano you're sitting at, a rehearsal, vinyl, or music playing in the room — anything you don't have as a file.

How long should I let it listen?

Give it at least ten seconds of continuous music. The estimate accumulates rather than resetting, so a full chord progression gives it far more to work with than a single held chord. The progress bar shows when enough frames have been gathered to show a result at all.

What does the confidence number mean?

It's the gap between the winning key and the runner-up. All 24 correlation scores sit in a narrow band, so the margin between first and second place says much more than the raw score. High confidence means one key clearly beat the rest; low confidence usually means the music is ambiguous or the relative major/minor is competing.

Why does it keep showing the relative minor instead of the major?

They contain exactly the same seven notes, so a pitch-class profile alone can't separate them — only which note feels like home does, and that's a rhythmic and harmonic cue rather than a spectral one. They share a Camelot number, so for mixing purposes the distinction rarely matters.

Does room noise affect the result?

Yes. Background chatter, traffic and air conditioning add energy across all pitch classes and flatten the profile, which lowers confidence. Get the mic closer to the source and reduce competing sound. Frames with no tonal content at all are skipped automatically.

Is my microphone audio stored?

No. Audio is analysed frame by frame in the browser and discarded immediately. Only the accumulated 12-number chroma profile lives in memory, and that's cleared when you reset or reload. Nothing is recorded and nothing is uploaded.