About this tool
Browser-based screen recorders and Chrome extensions save WebM, which iPhones, PowerPoint, and most editors will not open. WebM video (VP8/VP9) must be re-encoded to H.264 for MP4, so this one takes a little longer than a container swap, but the result plays everywhere.
About the formats: WebM is the open web video container (VP8, VP9, or AV1 video with Opus or Vorbis audio) produced by browser-based screen recorders and Chrome extensions. It works well in browsers, but iPhones, TVs, and most editing software will not open it. MP4 is the universal video container, usually holding H.264 video and AAC audio. It plays on every phone, browser, TV, and editing program, which is why most platforms ask for it.
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 WEBM files into the box above, or click to browse. Nothing is uploaded.
- Click Convert to MP4 and wait a moment.
- Download the results individually or all at once as a ZIP.
Frequently asked questions
Why is WebM to MP4 slower than MOV to MP4?
MP4 cannot hold VP8/VP9 video, so every frame must be decoded and re-encoded as H.264. Expect roughly real-time speed for 720p and slower for 1080p.
Will the quality drop?
The re-encode uses a high quality setting; you should not notice a difference for screen recordings.
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.