WebM
WebM is an open, royalty-free video container format designed for playback in web browsers. It is based on Matroska (MKV) and usually carries VP8, VP9 or AV1 video with Opus or Vorbis audio. Most modern browsers play WebM natively, though support on older Apple devices is limited.
Why it matters
WebM avoids codec licensing fees and is what many browsers produce when users record video in a web app. Teams that build in-browser recording get WebM files and must handle them. Without conversion, some viewers on older Apple devices may not be able to watch.
How it works
- A browser or encoder compresses video with VP8, VP9 or AV1 and audio with Opus or Vorbis.
- The streams are stored in a WebM file, a trimmed-down form of the Matroska (MKV) structure.
- Browsers can play the file directly in an HTML5 video element.
- For wide delivery, platforms often convert WebM into MP4 or adaptive streaming formats.
WebM vs MP4: which should I use?
Use MP4 for the widest device support and WebM when you need royalty-free codecs or are recording in the browser. MP4 usually carries H.264 or HEVC, which almost every device decodes. WebM carries VP9 or AV1, which modern browsers handle well but some older devices and TVs do not.
Does Safari support WebM?
Yes, current Safari versions play WebM, but support arrived late and older Apple devices may still fail. Safari on macOS added WebM in version 14.1, and Safari on iOS added it in iOS 15. If your audience includes older iPhones, provide an MP4 or HLS version as well.
Why do browser recordings save as WebM?
Browser recordings often save as WebM because the MediaRecorder API in Chrome and Firefox defaults to it. WebM's codecs are royalty-free and built into those browsers. Safari typically records MP4 instead, so a platform with in-browser recording should expect both formats.
Where it's used
SaaS products with in-browser recording, such as video messaging tools and e-learning assignment apps, receive WebM files from Chrome and Firefox and convert them so every viewer can watch.
By the numbers
- WebM was first released on May 18, 2010, initially with VP8 video and Vorbis audio, and Apple added native WebM support in Safari 14.1 on macOS in 2021. (WebM (Wikipedia))
