Question 1

Is my video uploaded to a server?

Accepted Answer

No. The conversion runs entirely in your browser using your device's own video engine. Your file never leaves your computer, and there is nothing for us to store or delete.

Question 2

Why convert to WebM?

Accepted Answer

WebM with VP9 is an open, royalty-free format that's well supported on the web and often smaller than MP4 at the same quality.

Question 3

Does WebM play everywhere?

Accepted Answer

Every modern browser plays it, including Safari on recent versions. Outside the browser it is patchier: some TVs, older phones and editors will not open it.

Question 4

How much smaller is VP9 than H.264?

Accepted Answer

Commonly 20 to 35 percent at the same visual quality, and more on flat, screen-recorded content. Encoding takes longer in exchange.

Question 5

Is WebM good for a website background video?

Accepted Answer

Yes, and it is the usual choice. Ship WebM first with an MP4 fallback in a second source tag for anything that cannot decode VP9.

Question 6

Is it free, and is there a watermark?

Accepted Answer

It is free with no watermark, no sign-up, and no export limit. There is nothing to buy here; the paid plan is on the Recast desktop app, which is a different product.

Question 7

How large a file can I convert?

Accepted Answer

The whole file is held in your device memory, so the ceiling depends on your machine. The upload panel shows the limit it worked out for your device, and it will tell you before it starts rather than failing halfway.

Question 8

Which browsers work?

Accepted Answer

Chrome, Edge, and other Chromium browsers have the broadest support. Firefox and Safari handle some operations. The page probes your browser on load and says plainly if a step is unsupported, so you never wait on a conversion that cannot run.

Question 9

Does it work on a phone?

Accepted Answer

It runs, but a phone has far less memory than a laptop, so keep the file small. For anything long, use a desktop browser.

Question 10

Does it work offline?

Accepted Answer

Once the page has loaded, yes. Nothing is fetched during the conversion, so it keeps working with the connection off.

Question 11

Why is my browser fan spinning?

Accepted Answer

Video work is CPU-heavy and it is happening on your machine rather than on a server. That is the trade for not uploading anything. Closing other tabs helps on a long file.

MP4 to WebM Converter

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