WebM is an open-source video format developed by Google and released in 2010, specifically designed for use on the web. It uses the VP8 or VP9 video codec (or the newer AV1) paired with Vorbis or Opus audio, all of which are royalty-free.
WebM was created as an open alternative to MP4, which relies on patented codecs. All major browsers - Chrome, Firefox, Edge, and Safari - support WebM playback natively, making it well suited for embedding video on websites.
WebM files encoded with VP9 are often slightly smaller than equivalent H.264 MP4 files at the same quality level, though encoding takes longer. The key difference is outside the browser: MP4 has much broader support on devices like Smart TVs, media players, and mobile apps. WebM is primarily a web format and may not play back on non-browser software without conversion.
WebM is commonly produced by browser-based screen recorders, some video conferencing tools, and web scraping of video content. It's also used by developers embedding video in web pages who want a royalty-free option.
WebM with VP9 encoding is efficient and produces good quality at lower bitrates. AV1-encoded WebM is even more efficient but is slower to encode and requires more processing power to decode.
You can convert WebM to MP4 directly in your browser - no software to install, no upload required. Your file never leaves your device.