FormatDrop
Video Format

WebM

WebM Video Format

WebM is Google's open, royalty-free video format designed for the web. It's smaller than MP4 for streaming, supported by all modern browsers, and the format screen recorders and web-based tools often use by default. Outside the browser, support is inconsistent.

What is WebM?

WebM was introduced by Google in 2010 as part of their push for a fully open, royalty-free web video ecosystem. It uses the Matroska container format (.mkv), adapted for web delivery. WebM supports two video codecs: VP8 (original, 2010) and VP9 (updated, 2013), both developed by Google. For audio, WebM uses Vorbis or Opus codecs. VP8 and VP9 are comparable in quality to H.264 and H.265 respectively, while being completely royalty-free — unlike the MPEG-LA-licensed H.264 codec used in MP4. WebM is the standard format for HTML5 `<video>` embeds alongside MP4, providing an open alternative. It's also the format output by many screen recording tools (including the Chrome tab capture API), browser-based video editors, and WebRTC recordings (video calls). Modern browsers all support WebM: Chrome, Firefox, Edge, and Opera play it natively. Safari supports it since version 14. The gap is in non-browser software: Windows Media Player, QuickTime, and many media players require codec packs to play WebM files.

WebM pros and cons

Advantages

  • Royalty-free and open standard
  • Smaller file sizes than H.264 MP4 at comparable quality
  • Supported by all modern browsers natively
  • Default format for screen recording and WebRTC recordings
  • Supports VP9 for high-quality, efficient streaming
  • Good support in VLC and other open-source players

Limitations

  • Windows Media Player cannot play WebM without codec packs
  • QuickTime and older Mac apps don't support WebM
  • Mobile apps (most iOS apps) have inconsistent support
  • Not accepted by most video hosting platforms as an upload format
  • Professional video editing software support is limited

When should you convert WebM files?

Convert WebM to MP4 when you need to play the video on Windows without VLC, share it via messaging apps, upload to video platforms (YouTube, Vimeo, Instagram), or use it in video editing software. MP4 is the universal video format. Convert WebM to GIF for short, looping clips that need to work anywhere without a video player. Convert MP4 to WebM when optimising video delivery for a website where you control the server.

Convert WebM files

WEBM→MP4
WEBM→GIF
MP4→WEBM

All FormatDrop conversions run entirely in your browser — no file upload, no server processing. Your files stay on your device.

WebM FAQ

Why can't I open a WebM file?
WebM is not supported by Windows Media Player, Apple QuickTime, or most default video apps on Windows and Mac. If you double-click a WebM file and it won't play, the easiest solutions are: (1) Download VLC media player, which plays WebM natively on all platforms, or (2) Convert the WebM to MP4 using FormatDrop — MP4 plays in every media player and app without additional software.
Is WebM better than MP4?
For web delivery in a browser, WebM with VP9 can achieve slightly better compression than H.264 MP4 while being royalty-free. For universal compatibility across all devices and software, MP4 is unambiguously better — it plays natively in Windows, macOS, iOS, Android, every media player, and every video platform. The trade-off is purely compatibility vs. openness/slight efficiency.
Does WebM support audio?
Yes. WebM supports Vorbis and Opus audio codecs. Opus in particular is excellent — it achieves CD-quality audio at very low bitrates and is used by Discord, Zoom, and WebRTC voice calls. So a WebM file can contain both video (VP8/VP9) and high-quality audio (Opus). When you convert WebM to MP4, the video is rewrapped to H.264/AAC codecs that MP4 expects.

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