WebM is an open video format for the web, supported by Chrome, Firefox and Edge. This converter runs entirely in your browser — the file is never uploaded.
Why convert MP4 to WEBM?
WebM is an open video format for the web, supported by Chrome, Firefox and Edge.
How it works
The video is encoded to VP9 (or VP8 as a fallback) with Opus or Vorbis audio. The conversion runs with ffmpeg compiled to WebAssembly, on your device.
Quality notes
VP9 encoding is slow in a browser; use MP4 for the widest compatibility, WebM when a site or tool asks for it.
Common use cases
Web pages and HTML5 video; tools and sites that require WebM.
Frequently asked questions
Does WebM play on iPhone?＋
Recent iOS versions play WebM in Safari, but MP4 is safer for Apple devices.
Why is it slower than MP4?＋
VP9/VP8 encoders are heavier than H.264, especially in WebAssembly.
Is my file uploaded?＋
No. The conversion runs in your browser; the file stays on your device.