Key Finder

Find the musical key of any song — free, private, in your browser.

100% in your browser — nothing is uploaded

Key Finder

This song key finder detects the musical key and scale of a track — C major, F# minor and everything between — without uploading anything. Drop in an audio file and the tool analyses its pitch content across the whole duration, builds a profile of which notes appear and how strongly, and matches that profile against all twenty-four major and minor keys. Knowing the key matters whenever two pieces of music have to coexist: harmonic mixing in a DJ set, layering a sample over a beat without dissonance, transposing a song into a singer’s comfortable range, or picking a backing track that will not clash with a vocal you already recorded. It is also the natural companion to tempo detection, which is why most people who need a key and BPM finder end up needing both numbers at once. Analysis runs locally with the Web Audio API, so demos and unreleased tracks stay on your machine. Key detection is probabilistic: tracks that stay in one key read cleanly, while music that modulates, leans heavily on ambiguous chords, or is dominated by drums may return a relative major or minor neighbour instead.

How to use the free key finder

1
Load an audio file
Drag in an MP3, WAV, M4A or FLAC. It is decoded in the browser — no upload, no account.
2
Analyse the pitch content
The key finder profiles which pitch classes appear across the track and weighs them by strength.
3
Read the key and scale
You get the detected key, whether it is major or minor, and the relative key you can also mix into.

Made for AI music creators

Layering a sample, transposing for a singer, or mixing two tracks harmonically? Find the key here, then pair it with the tempo from the BPM finder before you commit to an arrangement.

Key Finder: what people search for

Searched as a key finder song, a song key finder, a key detector, a music key analyzer and "how to find the key of a song" — and, most often of all, as a song key and bpm finder, because key and tempo are read together or not at all. DJs arrive by a different route again, looking for the Camelot wheel: the notation that turns "F minor" into 4A so compatible keys sit next to each other on a dial. This tool reports the musical key; pair it with the BPM finder for the full harmonic-mixing pair.

Key Finder at a glance

Runs: Entirely in your browser
Uploads: None — files never leave your device
Account: Not required
Cost: Free, no watermark
Output: Lossless WAV where audio is exported
Works offline: After the page has loaded

Why it works this way

The key finder runs on your machine

This song key finder detects the musical key and scale of a track — C major, F# minor and everything between — without uploading anything. Drop in an audio file and the tool analyses its pitch content across the whole duration, builds a profile of which notes appear and how strongly, and matches that profile against all twenty-four major and minor keys.

A free key finder with no signup

Layering a sample, transposing for a singer, or mixing two tracks harmonically? Find the key here, then pair it with the tempo from the BPM finder before you commit to an arrangement.

What the key finder handles

The cases people actually bring to it.

Load the audio file into this key finder. It analyses the pitch content of the whole track and reports the most likely key and scale, along with its relative major or minor, in a few seconds.
Reliable for music that stays in a single key with clear harmonic content. Tracks that modulate, sit on ambiguous chords, or are mostly percussion are harder, and the most common error is reporting the relative major or minor instead.
Every major key shares its notes with a minor key three semitones below — C major and A minor use identical pitches. Detectors confuse the pair regularly, and for mixing purposes either will usually work harmonically.
Yes. Run the file through this tool for the key and through the BPM finder for the tempo. Both run locally, so you can get both numbers for an unreleased track without uploading it anywhere.

Who uses it

Who reaches for the key finder

Producers

A quick answer mid-session without opening a DAW project.

DJs

Checking a track before it goes into a set.

Video editors

Preparing audio to sit under a cut.

Students

Learning what the numbers mean by watching them change.

Key Finder — frequently asked questions

How do I find the key of a song?

Load the audio file into this key finder. It analyses the pitch content of the whole track and reports the most likely key and scale, along with its relative major or minor, in a few seconds.

How accurate is automatic key detection?

Reliable for music that stays in a single key with clear harmonic content. Tracks that modulate, sit on ambiguous chords, or are mostly percussion are harder, and the most common error is reporting the relative major or minor instead.

What is a relative key and why does it matter?

Every major key shares its notes with a minor key three semitones below — C major and A minor use identical pitches. Detectors confuse the pair regularly, and for mixing purposes either will usually work harmonically.

Can I use this as a key and BPM finder together?

Yes. Run the file through this tool for the key and through the BPM finder for the tempo. Both run locally, so you can get both numbers for an unreleased track without uploading it anywhere.

Why do DJs need the key of a track?

Harmonic mixing means blending tracks whose keys are compatible — the same key, the relative major or minor, or a neighbour a fifth away. Mixing clashing keys is what makes a transition sound sour even when the beats are locked.

Does the key finder work on vocals only or acapellas?

It works better on material with harmonic content than on isolated drums, and an acapella with a clear melody usually reads correctly. Very short or heavily processed clips give the algorithm less to work with.

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