All converters
Nine conversions, one engine. Pick a pairing below — each runs entirely inside your browser with no upload and no size limit.
Everything runs in your browser
Every converter on this site uses the same engine: a build of ffmpeg compiled to WebAssembly that runs inside the page. Your file is read from disk into the tab's memory, processed there, and written back out as a download.
That design has three consequences worth knowing. There is no upload, so your video never touches a server and privacy is structural rather than promised. There is no file size limit, because no one is paying for storage. And there is no queue, because the work happens on your machine rather than a shared one.
The trade is that conversion speed depends on your device. A recent laptop encodes faster than a phone, and a long 4K file will take real time on either. For batch work, the ffmpeg command on each page does the same job locally.
Do not see the format you need?
New conversions are added regularly. Email contact@webm-mp4.com with the pairing you need and it will go on the list.