Video format

WEBM converter

A .webm file is an open, royalty-free video container built specifically for the web. It restricts itself to free codecs, VP8, VP9, or AV1 for video with Vorbis or Opus for audio, so any browser can play a .webm without patent licensing concerns.

Private for supported formats — processed in your browser

Convert supported files

Runs on your device

Drop WEBM files here

Batch files can each use a different output. Nothing uploads for local conversions.

Working inputs include camera RAW, browser-local audio/video, PDF, CBZ/CBR comics, office documents, ebooks, markup, 3D models, structured text, images, and archives.

Where WEBM comes from

Google launched WebM in 2010 after acquiring On2 Technologies, releasing the VP8 codec and a trimmed-down Matroska container under free licenses. VP9 and later AV1 kept the project competitive with H.265 while remaining royalty-free.

How WEBM works

Structured as a deliberately restricted subset of Matroska's EBML layout
Permits only VP8, VP9, or AV1 video paired with Vorbis or Opus audio
VP9 encodes can carry an alpha channel, enabling video with real transparency
The browser MediaRecorder API emits WebM directly, making it the native format of in-browser capture

When to use WEBM

Serving HTML5 video without codec license fees
Building transparent video overlays for web design
Saving screen or webcam recordings captured through browser APIs
Replacing heavyweight animated GIFs with far smaller files

Strengths and limitations

Strengths

Free of patent royalties end to end
VP9 and AV1 deliver excellent compression efficiency
Direct output format of browser recording APIs
Alpha-channel support that MP4 workflows lack

Limitations

Older iPhones and legacy Safari versions cannot play it
Hardware support outside browsers, in TVs and car systems, is thin
Professional editing suites often demand conversion before import

Compatibility

Chrome, Firefox, and Edge have played WebM for over a decade, and Safari added playback in 2021 starting with version 14.1 on macOS, with iOS following in iOS 15. Beyond browsers the picture thins out quickly, since many televisions, set-top boxes, and editors still expect MP4.

Only a minimal set of Matroska tags such as title and language is defined for WebM; the spec deliberately omits attachments and rich tagging.