At a glance
- Accepts
- MP3, WAV, M4A, AAC, OGG, Opus, FLAC, and the audio track of a video
- Outputs
- Tempo in BPM with half and double time, key with relative key, Camelot and Open Key codes, a confidence for each, and a beat-grid preview
- Where it runs
- Entirely in your browser, on your device
- What leaves your device
- Nothing - the file never leaves your device
- Limits
- Gives one tempo and one key per file: songs that change tempo get an average, and songs that change key get the most-used key; half or double the expected tempo and the relative major/minor are the usual misses
- Account
- Not required - there is no sign-up
- Price
- Free, with no watermark and no usage cap
- Made by
- Visrut
- Last updated
- 12 October 2026
Drop in a song and this tells you its tempo in beats per minute and its musical key, with the Camelot code DJs use for harmonic mixing. It also shows half and double time, the relative key, and how confident each answer is. Everything runs in your browser, so the song is never uploaded. A tap tempo button lets you check the result by ear.
How to use it
- Drop in an audio file, or a video to analyse its soundtrack. The result appears in a few seconds.
- Read the BPM and key. If the tempo feels twice as fast or slow as you expect, use the half-time or double-time figure.
- Press play with clicks to hear the detected beats over the music, or tap along with the tap tempo button to check.
How it works
For the tempo, the tool measures how sharply the sound gets louder in each slice of time, which peaks on drum hits and note attacks, then looks for the spacing at which those peaks repeat most strongly. A beat tracker then places each beat, and the average gap between beats gives the BPM to a fraction of a beat per minute. For the key, it measures how much of each of the 12 notes the song contains, after allowing for recordings that are not tuned to A = 440 Hz, and compares that against the typical note pattern of each of the 24 major and minor keys (the Krumhansl-Schmuckler method, using key profiles from Krumhansl and Kessler and from Albrecht and Shanahan). The closest match is the key.
When the answer can be wrong
- Half or double tempo is the most common disagreement, for any BPM finder. Both are shown so you can pick the one that matches how the track is counted in its genre.
- Songs that speed up, slow down, or have no steady drum (live recordings, classical, rubato ballads) get an average tempo and a note saying so.
- A major key and its relative minor share the same notes, so they are easy to mix up. The relative key and the runner-up are always listed.
- Songs that change key part-way get the key used most overall.
Making a remix or a karaoke track?
Once you know the tempo and key, you can take the song apart: Remove Vocals makes an instrumental or a cappella version, and the Voice / Music Splitter separates speech from background music. Both also run in your browser.
Frequently asked questions
How accurate is the BPM and key?
On music with a steady beat the tempo is usually right to within a fraction of a BPM: on our click-track tests at 90, 120, 128 and 140 BPM it read 90.0, 120.0, 128.0 and 140.0. The common miss is not a wrong number but half or double the tempo you expect, which is why both are shown. Key detection is harder. It works out which notes the song uses most and matches them to the 24 major and minor keys, so it is reliable on songs that stay in one key and less so on songs that change key, borrow chords, or have hardly any harmony (a drum loop, rap over a beat). The confidence shown next to each answer tells you how clear-cut it was.
What does the Camelot code mean?
The Camelot wheel is a DJ shorthand for keys that mix well together. Each key gets a number from 1 to 12 and a letter: B for major, A for minor. C major is 8B and A minor is 8A. Tracks with the same code, the same number with the other letter (a key and its relative), or a number one step up or down are usually in harmony when you mix from one to the other.
Why does it say 87 BPM when my track is 174 (or the other way round)?
Tempo has an octave problem: a beat at 87 BPM and one at 174 BPM line up perfectly, and which one you feel depends on the genre and on where you tap. Drum and bass is usually counted at 174, while a hip-hop track at the same speed would be called 87. The tool picks the one that is more likely for most music and shows half time and double time next to it. If you hear it differently, use the alternative, or tap along to check.
Is my song uploaded anywhere?
No. The file is decoded and analysed inside your browser tab, in a background worker, and nothing is sent to a server. You can disconnect from the internet after the page loads and it still works.
What is the relative key, and why is it listed?
Every major key shares its notes with one minor key, its relative: C major and A minor use exactly the same seven notes. Telling them apart depends on which note the music treats as home, which is the most common mistake for any key finder. If the answer sounds wrong, the relative key is the first thing to try.
My song changes tempo. What does the BPM mean then?
If the beat drifts or the song speeds up and slows down (live recordings, classical music, songs with a slow intro), the tool says so, and the BPM it shows is an average. For the tempo of one section, use the tap tempo button while that part plays.
What files can I use?
Anything your browser can play: MP3, WAV, M4A, AAC, FLAC, OGG and Opus, or a video file (MP4, MOV, WebM), in which case the audio track is analysed. Songs up to about half an hour work on most devices.
How does the tap tempo button work?
Tap it (or press the T key) in time with the music. After a few taps it shows the average tempo of your last eight taps. Stop for two seconds and the next tap starts a new count. It is a quick way to check whether the detected tempo, or its half or double, matches what you hear.