Add your files
Drop one MP4 or two hundred. Batch conversion is not a paid feature here.
Convert MP4 to WEBM
A video is going on a website as a background or an inline clip, and the page weight matters more than universal compatibility.
Runs on your deviceFreeNo sign-upBatch supported
Where the streams already fit the target container this is a lossless remux, which is close to instant. Otherwise it re-encodes, which in a browser is slow — keep it under a few hundred MB and send long videos to the cloud engine.
Waiting for files/Engine: on-device/Network requests made: 0
What actually changes
MP4 and WEBM are not the same picture in two wrappers.
H.264 is re-encoded to VP9 and AAC audio to Opus. VP9 typically reaches the same visual quality at 30 to 50 percent fewer bits, which is the entire reason to do this.
Worth knowing first
VP9 encoding is slow, often several times slower than H.264 for the same clip, and it has no hardware encoder on most machines. A long video is a background job, not something to wait on.
Questions
MP4 to WEBM, answered
Do all browsers play WEBM?
All current ones do, including Safari for VP9. Outside browsers, support is thin, so keep an MP4 for anything downloadable.
Should I serve both?
Yes, through multiple source elements. The browser picks the first it can play and MP4 remains the safe fallback.
How to convert MP4 to WEBM
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Choose your settings
WebM Video is lossy, so the quality control decides the trade between size and fidelity.
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Download
Instant, because the file never went anywhere. Nothing expires, since nothing was stored.