Overview

video/webm is the media type for video in the open WebM container led by Google, commonly wrapping VP8/VP9/AV1 video and Vorbis/Opus audio. Royalty-free and web-friendly, it is widely used for autoplay background videos and short clips.

Details

WebM is the Matroska (MKV) container refined for the web, carrying efficient open codecs like VP9 and AV1 that are often smaller than H.264 MP4 at equal quality. However, support is limited on older Safari and some devices, so using it alone is risky. The standard practice is to list both WebM and MP4 `<source>` elements inside `<video>` and let the browser choose a playable one.

Like other web video, seeking and partial playback need `Accept-Ranges: bytes` and `Range` (206) support. Replacing heavy animated GIFs with autoplay, muted, looping WebM/MP4 — cutting file size to a fraction — is a hallmark optimization here.

Syntax

e.g. Content-Type: video/webm

File extensions

Notes

• Support is limited in some environments such as Safari, so always include a video/mp4 fallback source in <video>.
• Seeking and partial playback require Accept-Ranges/Range (206) support.
• Ideal as an autoplay muted loop replacement for animated GIFs, saving substantial bandwidth. Already compressed, so transport gzip is pointless.

Related types

Related headers