WebM is an open, royalty-free video format developed by Google. It uses the VP8 or VP9 video codec and Vorbis or Opus audio codec. All modern browsers support WebM natively.

Is WebM smaller than MP4?

Generally yes. WebM with VP9 encoding produces files 30-40% smaller than H.264 MP4 at equivalent visual quality, which is why it's preferred for web publishing.

Are my files uploaded to a server?

No. All conversion runs in your browser using WebAssembly. Your files stay on your device.

Yes, completely free with no account needed.

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MP4 to WebM Converter Online Free

Convert MP4 video files to WebM for web publishing, HTML5 video tags, and open-source platforms. WebM is a royalty-free format developed by Google, supported by all modern browsers, and produces smaller file sizes than MP4 at equivalent quality for web use.