Free · no sign-up
Convert MP4 to WebM
Turn an MP4 into WebM (VP9 + Opus) for websites and HTML5 video. Your file is never uploaded — it's processed right here in your browser.
How it works
01. Add your MP4 file
Drop or choose your MP4 file. Other video formats work too.
02. Leave the rest to us
Nothing to choose. Video becomes VP9 and audio becomes Opus.
03. Download the WebM
Hit Convert and download your WebM file when it's ready.
Why convert to WebM?
WebM is a royalty-free web standard. VP9 is lighter than H.264 at the same quality, which suits background videos and product demos on web pages.
How the conversion works
H.264 video is re-encoded to VP9 and AAC audio to Opus, frame by frame. If your device has no VP9 encoder, VP8 is used instead.
Frequently asked questions
Does WebM play in Safari?
Recent Safari on macOS and iOS plays VP9 WebM. To cover older devices, add an MP4 source next to it on your page.
Is my video stored anywhere?
No. The file never leaves your device — it's processed inside this tab with WebCodecs. Close the tab and nothing is left behind.
Is there a file size limit?
Up to 2 GB per file. The result is held in your browser's memory, so on devices with little RAM smaller files are safer.
Which browsers are supported?
Recent Chrome, Edge, Safari and Firefox. Speed depends on your device — desktop Chrome and Edge are usually the fastest.
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