Change the speed and pitch of any song

Speed and pitch are two different things, and this changes them separately: slow a solo to half speed with the pitch untouched, or move a song into your own key without it getting faster. Everything plays while you move the controls, so you hear the change immediately instead of exporting a file to find out. Drag across the waveform to loop the bars you are working on.

  1. Your track

    Drop a song or a video here

    MP3WAVM4AFLAC

    Your files are never uploaded.

  2. Play with it

  3. Your file

How to change speed and pitch

  1. Add your track

    Drop in an MP3, WAV, M4A, FLAC or a video file. It is read by your browser and never uploaded.

  2. Play with it

    Press play and move the speed and pitch faders while it runs. Start from a preset if you want — slowed and reverb, nightcore, practice — then adjust from there. Drag across the waveform to loop a section.

  3. Take the file

    When it sounds right, export it. You get a 320 kbps MP3 and a lossless 24-bit WAV of exactly what you were hearing.

What you get

You hear it while you change it

Every other tool for this makes you pick a setting, wait for a render, listen, and go back. Here the track keeps playing while you drag, so the answer to "is that too much?" takes a second rather than a round trip. There is no model and nothing to download — the processing is a 113 KB audio engine that loads with the page.

Speed and pitch move independently

Slowing a recording down normally drops its pitch, the way a record does at the wrong speed. This separates them, so you can take a fast solo to half speed in the original key and actually learn it — or transpose a song without changing its tempo. There is a switch to weld them back together if you want the turntable effect on purpose.

Voices still sound like people

Shifting pitch normally moves the resonances that make a voice recognisable, which is where the chipmunk effect comes from. Turn on the natural-voice setting and those stay put, so a key change sounds like the same singer in a different key. Leave it off for nightcore, where the chipmunk is the point.

Loop the four bars you are learning

Drag across the waveform to mark a section and it repeats, at whatever speed you set. Export while a loop is set and you get just that section — a practice file of the hard bit, rather than the whole song.

Frequently asked questions

Is my music uploaded anywhere?
No. The file is decoded and processed by your own browser and never leaves your device. You can watch the network tab while you use it.
Which model does this use?
None. The time-stretching is Signalsmith Stretch, a 113 KB audio engine that runs in your browser — not a neural network, and nothing to download separately. For this job that is the stronger claim: it runs live, which no model does, and there is nothing to download at all.
How long does it take to make the file?
Roughly a second of work for every twelve seconds of output, plus about the same again to encode the MP3 — so a four-minute song is around fifteen seconds in total. Playing with the controls is instant; only the final file takes any time.
Why does slowing something down sound worse the further I go?
Because the audio between the original samples has to be invented, and the more you stretch the more of it is invented. Half speed is very clean. A quarter speed is usable for picking out notes but will sound smeared on cymbals and reverb tails. That is the nature of time-stretching, not a limit we chose.
Can I use this on a video file?
Yes — drop the video in and the audio is taken from it. What comes back is audio only, so this is for pulling a track out and changing it, not for re-timing the video itself.
What is the difference between the MP3 and the WAV?
The MP3 is 320 kbps, which is the top of the format and small enough to send. The WAV is 24-bit and lossless, which is what you want if the file is going into an editor for more work. If you are only listening, take the MP3.