Convert an MP4 to WebM for smaller file sizes and open-source-friendly web delivery.
WebM — typically VP9 or AV1 video with Opus audio — is the format Google pushes on the open web. It's often smaller than an equivalent-quality MP4 and is the preferred delivery format for Chrome, Firefox, and Android. If you're self-hosting video on a website, WebM gives you smaller files and royalty-free codecs.
Converting MP4 to WebM is a full re-encode (MP4 and WebM share no codecs). That takes real compute — for a 10-minute clip, expect a minute or two on modern hardware. We use your browser's WebCodecs encoders which are GPU-accelerated where possible.
MP4 is the most widely supported video container, based on the ISO Base Media File Format. It can carry H.264, H.265 and AV1 video with AAC, MP3, or Opus audio.
WebM is the open web's video format. Smaller than MP4 at equivalent quality and plays natively in all modern browsers.
Drag a MP4 onto the converter above, or click the box to pick one from your device.
We've preselected WebM as the output format. Change it from the dropdown if you want a different target.
Click Convert and wait for the progress bar to finish. Download the WebM when it's ready.
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