Convert WebM files to MP4 instantly and privately. File Converts runs entirely in your browser, so your WebM is never uploaded to any server.
No upload Instant Free
Runs in your browser via WebAssembly — your media is never uploaded. The FFmpeg engine (~30MB) downloads once on first use, so the first conversion takes a little longer.
Works offline after you have used it once: the engine downloads the first time and is kept. About 30 MB, once.
Privacy, proven — live
Online
0 BUploaded to our servers
0Requests carrying your data
0Files stored by us
—Processed on your devicedrop a file
Conversions run entirely in your browser. Turn off your Wi-Fi and try it — it still works. Nothing leaves this device.
WebM is Google's open container, built for the web and holding VP8, VP9 or AV1 video. Browsers play it natively, which is why so much web video and so many screen recordings and downloads arrive in this format. Almost nothing outside a browser does: video editors, phones' native players, messaging apps and social uploads generally want MP4.
Unlike MOV or MKV, this one is a real re-encode. VP9 and AV1 are not codecs MP4 carries in practice, so the video has to be decoded and re-encoded as H.264. That takes longer than a remux and is lossy, so work from the highest-quality WebM you have rather than one already converted once.
The result plays essentially everywhere, at the cost of a larger file: H.264 is less efficient than VP9 and considerably less efficient than AV1, so expect the MP4 to be bigger than the WebM it came from.
How to convert WebM → MP4
01
Drop your WebM file into the converter above — it stays on your device.
02
Choose MP4 as the output. File Converts picks the smartest settings automatically.
03
Click Convert and download your MP4 file instantly.
Frequently asked questions
WebM is an open, web-optimized video format. MP4 is the most widely supported video container — it plays virtually everywhere. Converting WebM to MP4 keeps your content while giving you MP4's strengths.
Yes — it's completely free with no sign-up and no limits, because the conversion runs on your own device.
No. File Converts converts your WebM to MP4 entirely in your browser. Your file never leaves your device, which makes it both private and instant.
Yes. We use high-fidelity rendering and let you control output quality where it applies, so your MP4 stays crisp.
Yes. The converter is mobile-first and works in any modern browser on phone, tablet, or desktop — and offline once its engine has downloaded on your first use.
