WEBM file format: what it is and how to use it

WebM is the open web video container: a Matroska subset carrying only royalty-free codecs (VP8/VP9/AV1 + Vorbis/Opus) built for HTML5 video. Learn when to use it and what to choose instead.

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What is a WEBM file?

A .webm file is video in the WebM container, a Matroska subset Google defined in 2010 for the open web: only royalty-free codecs allowed inside (VP8, VP9, AV1 video; Vorbis, Opus audio), streamed beautifully and played natively by every modern browser. It is the patent-free answer to MP4, built for <video> tags.

When should you use WEBM?

  • Open web video: royalty-free delivery in all modern browsers.
  • AV1 content: the container that carries the newest open codecs.
  • Small screen recordings: what many capture tools emit by default.

When is another format a better fit?

For universal playback, meaning TVs, old devices and social apps, MP4 is the safe container. For multi-track archives MKV (its parent) holds more; for editing pipelines MOV. WebM is the web's lane, not the world's.

The short version: WEBM is the open, patent-free video container, perfect for the browser. Convert to MP4 when it leaves one.

How to open a WEBM file

On Windows

Double-click the file, or open it with VLC.

On macOS

mpv opens WEBM files on macOS.

In your browser

Open WEBM files right in a browser tab or with the dexrr viewer. No install, no upload.

Also opens in

  • Any web browser
  • VLC
  • mpv

View WEBM files

A quick preview or a new format. No install, no upload.

View WEBM files Preview and inspect WEBM files WEBM to MKV Matroska video WEBM to MP4 MPEG-4 Part 14 WEBM to MOV QuickTime movie

WEBM technical details

Full name
WebM video
Extensions
.webm
MIME type
video/webm, audio/webm
Magic bytes
1A 45 DF A3 (EBML)
Compression
Lossless or lossy
Developer
Google
Specification
www.webmproject.org

WEBM questions, answered

How do I open a .webm file?

Every modern browser plays it natively; VLC, mpv and editors handle it too. dexrr plays and converts webm files directly in your browser.

Can I convert WebM files online?

Yes, dexrr converts webm locally in your browser: WebM to MP4 for universal playback or WebM to MKV for archives.

Is WebM better than MP4?

For open-web delivery, arguably, since it is royalty-free and often smaller at quality. For universal playback, MP4 wins. Different destinations.

Why won't my TV play .webm?

Hardware players whitelist codecs, and many never implemented VP9/AV1. Convert to MP4 with H.264 for device playback.

Is the WebM format outdated?

No, it is the maintained open video standard and the container of AV1, the codec with the strongest streaming future.