About this tool
Turn a slow screen recording into a brisk demo, compress a long process into a timelapse, or slow a clip down to study it. Video and audio are retimed together and the audio pitch is corrected, so voices stay natural instead of turning into chipmunks or growls. The result is a standard MP4.
Everything happens inside your browser. Your file is never uploaded to a server: the conversion runs on your own device using WebAssembly, and the result is downloaded straight from memory. Close the tab and nothing is left behind.
How to use it
- Drop your MP4 file into the box above, or click to browse. Nothing is uploaded.
- Adjust the options if you want; the defaults suit most files.
- Click the button and wait a moment.
- Download the result.
Frequently asked questions
Does slowing down add frames?
No, frames are shown for longer, so 0.25× looks choppy on low-frame-rate sources. 0.5× on 60 fps footage looks smooth.
Can I remove the audio instead of retiming it?
Yes: run the clip through Mute Video first.
Is this really free?
Yes. The site is supported by ads, and there are no limits on how many files you convert.
Are my files uploaded anywhere?
No. The converter runs entirely in your browser. Files stay on your device, which also makes it faster than upload-based converters for anything larger than a few megabytes.
Is there a file size limit?
The only limit is your device's memory. Images and audio of any normal size are fine; for video, files under about 500 MB work well on most laptops and phones.
Which browsers are supported?
Current versions of Chrome, Edge, Firefox, and Safari on desktop and mobile. Very old browsers without WebAssembly support will not work.