Convert MP4 to WebM

Re-encodes video to WebM, the royalty-free format browsers play natively.

What to expect

A full re-encode, so it takes time and loses a little quality. Hardware players often cannot play WebM.

Why convert MP4 without uploading

Most online converters take your file, send it to their servers, convert it there and hand back a download link. That means your document sits on someone else's disk, subject to their retention policy and their breaches. It also means you cannot use them offline, and cannot use them at all for anything confidential.

frogConvert does the conversion in the page itself, with FFmpeg compiled to WebAssembly. There is no upload step because there is no server. You can disconnect from the network and it still works.

About the formats

MP4

The default video container almost everywhere, normally holding H.264 video and AAC audio. Its ubiquity, not its technical merit, is the reason to choose it. More about MP4 files.

WebM

A trimmed-down Matroska carrying VP8/VP9 or AV1 video with Vorbis or Opus audio, designed as a royalty-free web format. Browsers play it natively; hardware players often do not. More about WebM files.

Common questions

Is my file uploaded when converting MP4 to WebM?

No. The conversion runs entirely in your browser. The file never leaves your device, there is no server to upload to, and the page works offline once loaded.

Is MP4 to WebM conversion free?

Yes, with no account, no watermark and no file limit per day. frogConvert is open source and there is no server cost to recover, because your device does the work.

How large a file can I convert?

Up to 2 GB for a single file, 500 MB total per batch, and 300 files at once. The practical limit is your device's memory, since everything is processed locally.

What is lost converting MP4 to WebM?

A full re-encode, so it takes time and loses a little quality. Hardware players often cannot play WebM.