WebM file format
WebM (Google)
WebM is Google's royalty-free web video format, based on Matroska with VP8, VP9 or AV1 video and Opus or Vorbis audio. Browsers play it natively, but many editors and phones prefer MP4.
| Property | WebM |
|---|---|
| File extensions | .webm |
| MIME type | video/webm |
| Introduced | 2010 by Google |
| Typical video codecs | VP8, VP9, AV1 |
| Typical audio codecs | Vorbis, Opus |
| Plays in web browsers | Yes — Chrome, Edge, Firefox, Safari 14.1+ |
| Compatibility | Browsers, Android; limited in editors and on iPhone apps |
| Best for | Royalty-free web video, screen recordings |
What is a WebM file?
WebM was announced by Google in 2010 as an open, royalty-free alternative to H.264 for HTML5 video. It's a subset of Matroska restricted to VP8, VP9 or AV1 video and Vorbis or Opus audio. Browser screen recorders and many web tools save WebM by default.
Strengths and weaknesses
WebM plays in every modern browser and avoids codec licensing fees. VP9 and AV1 compress very efficiently. On the other hand, Premiere Pro, iMovie, WhatsApp and many TVs don't accept WebM, and encoding VP9 or AV1 is slow.
When should you use WebM?
Use WebM for web pages and when an app records in WebM. Convert to MP4 to edit, share on social media or play on iPhones and TVs.