Runs on your device · Your file never leaves your device.
WebM is the open video format that browsers play natively and that many web builders, forums and Linux tools prefer. This page converts an MP4 into WebM on your device.
The output is VP8 video with Opus audio, the WebM pairing current versions of Chrome, Edge and Firefox play. Encoding runs on your own processor rather than a server, so a short clip finishes in seconds and an hour-long film takes a good while. A film too big for your device’s memory is converted in shorter parts, one after another, right here on the page.
Nothing is uploaded, and the page works offline once the video engine has loaded.
How to convert MP4 to WebM
Add the MP4.
WebM is already selected as the output.
Press Convert — the encoder works on your device.
Download the WebM.
Supported formats and limits
Input
MP4, MOV and other common video
Output
WebM (VP8 + Opus)
Where it runs
In your browser; nothing uploaded
Not for: Long films — encoding on a phone takes a while; keep it to clips.
Frequently asked questions
Are my files uploaded to a server?
No. This conversion runs entirely inside your browser using your own device’s processing power. The file never leaves your computer or phone, which is why it also works when your connection drops.
Why does it take a while on long videos?
Every frame is re-encoded on your device. On a phone, keep clips short; on a laptop a few minutes of video is comfortable.
Should I use WebM or MP4?
MP4 for messaging, phones and social apps; WebM when a web page, a wiki or an open-source tool asks for it.