Convert WebM to MP4

How it works

1. 1

   Add your WEBM file

   Drop, pick, or paste it. It stays on your device.

2. 2

   Convert

   We re-encode it to MP4 right here in your browser.

3. 3

   Download

   Save the MP4 file.

WebM is a web format, and that is its whole problem

WebM exists so browsers can stream video without anybody paying codec royalties, and at that job it is excellent. It carries VP8, VP9, or AV1 video with Opus audio, all royalty-free, which is why so much of what you save off the web arrives as one.

Outside a browser, that same design turns into friction. Video editors are lukewarm about VP9, phones would rather not decode it, and a good deal of software simply refuses the container outright. So the file plays flawlessly in the tab you downloaded it from and then fails everywhere you actually wanted to use it.

Converting to MP4 with H.264 inside trades a little efficiency, since H.264 is an older and less clever codec, for the fact that absolutely everything will open it. That is nearly always the right trade for a file you intend to edit, send, or upload somewhere else.

Why nothing uploads

Other tools send your video to their servers, which costs them money per file, so they add watermarks, cap file sizes, and make you sign up. This tool does the work right here in your browser using your own device. Your file is never uploaded, so there is no wait, no watermark, no size limit, and no account.

Questions

Why did my download come out as a WebM?

Because that is what the site was serving. WebM is royalty-free, so it is cheap for a platform to deliver, and browsers all support it natively.

Will the MP4 be bigger?

Usually slightly, yes. VP9 and AV1 are more efficient than H.264, so the same quality costs a few more megabytes in an MP4. Universal support is what you are buying.

Can this be a rewrap instead?

No. MP4 cannot carry VP9 or Opus in a way anything would accept, so the streams genuinely have to be re-encoded.

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