Free video converter
WebM to MP4 Converter
Convert a WebM video to the more widely compatible MP4 (H.264/AAC) format directly in your browser. The conversion runs on a WebAssembly build of FFmpeg loaded on demand — nothing is uploaded to a server.
Convert WebM to MP4
Drop a WebM video here, or click to choose a file
Processed locally in your browser — nothing is uploaded.
100% local — your file never leaves your device. The first conversion downloads a ~30MB FFmpeg engine to your browser; later conversions are fast.
Frequently asked questions
Is this WebM to MP4 converter really free?
Yes, entirely free, with no account, watermark, or file limit imposed by a server — because there is no server involved.
Does my video get uploaded anywhere?
No. The video is processed locally in your browser using a WebAssembly build of FFmpeg. It never leaves your device.
Why convert WebM to MP4?
MP4 (H.264/AAC) is supported by virtually every device, video editor, and platform, while WebM playback support is less universal, especially on older or non-browser software.
Why does the first conversion take longer?
Your browser downloads the FFmpeg WebAssembly engine (roughly 30MB) the first time you use this converter. It's cached for the rest of your session.
Doing this by hand every week? That's exactly what I remove.
If this conversion is one small step in a bigger workflow — say, files arriving by email, getting converted, renamed and filed by a person every time — I build software that does the whole thing automatically. My clients get back up to 18 hours a week this way.
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