How it works
It listens for which notes the song leans on. Over the whole song it adds up how much each of the 12 notes sounds, from the bass to the top of the melody, and compares that balance with how often each note is used in every major and minor key. Those key profiles come from music research, so it needs no list of songs and nothing to learn from. The best match is the key.
The tempo comes from the same method as our BPM finder, which is DOT’s own. It all runs on your computer, in this page: your file is never uploaded.
Why it sometimes says “or C major”
Every minor key shares its notes with a major key, its relative: A minor and C major use exactly the same seven notes. What decides between them is where the song comes home, and a finder can only guess at that from how often each note sounds. When two keys fit almost equally well, it shows both. Play the first chord of the chorus: if it feels like home, that’s your key.
The Camelot number
Next to the key you’ll see a number and a letter, like 8A. That’s its place on the Camelot wheel, which DJs use for harmonic mixing: songs with the same number, or one step either way, blend without clashing. A is minor and B is major, so 8A (A minor) and 8B (C major) are relatives.
How accurate is it?
Finding the key is harder than finding the tempo, for every finder. On 16 songs by Kai Williams, it named the same key as DOT on 14. On about a thousand tagged sample loops, which are harder because many are a single instrument or a voice, it named the exact key about half the time. Most of the misses were near: the relative major or minor, or the key a fifth away.
So treat it as a strong first guess, and check it with your ears. If you need the exact BPM by feel, our tap tempo page helps too.
When it finds no key
Drums, speech and noise have no key, and it says so rather than guessing. A song that changes key gets the key it spends the most time in. If the start is just drums, cut it off and try the part where the chords come in.
Need the chords too?
DOT records whatever your Mac is playing, from a video, a preset demo or a friend’s session, and gives you its key, tempo and chords. You drag the clip straight into your DAW, and the chords come out as MIDI.
Questions
Is my song uploaded anywhere?
No. The finder runs in your browser. Your file is read on your computer and never sent to us or anyone else.
Which files work?
MP3, WAV, AIFF, M4A and FLAC all work. Video files with sound, like MP4 and MOV, usually work too.
Why does it say “or” with a second key?
Because both fit almost equally well, most often a minor key and its relative major. They share every note, so only your ear can tell which one the song treats as home.
What does the Camelot number mean?
It’s the key’s place on the Camelot wheel that DJs use. Same number or one step away mixes smoothly; A is minor, B is major.
Can it find the chords?
Not here. DOT finds the chords of anything your Mac plays, half bar by half bar, and saves them as MIDI.
Is there a limit?
No sign-up, no limit and no watermark. It’s free.