MP4 to WebM Converter - free, no upload, in your browser

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Why this runs on your computer

There is no upload: The work happens in this tab. Your file never travels, so there is no copy of it anywhere but your own disk.
Nothing to delete later: Sites that upload promise to delete your file afterwards. That promise only matters because the file was theirs to hold.
It works with the Wi-Fi off: The honest test. Turn off your connection and the tools keep working, because everything they need is already here.

Drop your file hereto convert it

Nothing is uploaded - the tools run right here

Applies to every loaded image

Look Strength 100% Brightness Contrast Saturation Vibrance Vignette

Max width

Format Shape

Colours 6 Detail 1 Smooth curves

Shape Size Across Down Border

Text Where

100%

Questions

Why convert MP4 to WebM?

MP4 is the format everything plays, and the safe answer when you are not sure. WebM is small and made for the web, though older players and editors ignore it. Converting is how you move a file from the first situation to the second.

What will the WebM file contain?

VP8 video and Opus sound, which every current browser plays in a web page.

Is the picture re-encoded?

Yes. WebM cannot carry the H.264 video an MP4 file normally holds, so the picture is encoded again, at a quality setting high enough that the difference is hard to see.

Is the sound kept?

Yes. The audio track comes across with the picture - copied when WebM can hold it as it is, converted when it cannot.

How long does it take?

Repackaging takes seconds. A full re-encode runs in this tab on one processor core, so a long HD video takes a while - but there is no upload or download to wait for.

Convert MP4 to WebM without uploading it

How to convert MP4 to WebM

Why this one stays private

Questions

The same tool, other formats