Video format
What is a .webm file?
WebM is an open, royalty-free video format designed for the web. It carries VP8, VP9 or AV1 video with Opus or Vorbis audio, and browsers play it directly.
It’s what many screen recorders and browsers produce. Outside the browser support is uneven, which is the usual reason to convert it to MP4.
fileclay opens and writes WebM
WebM vs MP4 vs GIF
| WebM | MP4 | GIF | |
|---|---|---|---|
| Audio | Yes | Yes | No |
| Transparency | Yes | No | On or off |
| File size | Small | Small | Large |
| Plays in | Browsers | Everything | Everything |
| Best for | Video on the web | Sharing anywhere | Short loops |
When to use WebM
Good for
- Video embedded on a website
- Animations with transparency
- Replacing heavy GIFs
Not a good fit
- Sending to people who will open it outside a browser
- Editors that don’t import it
- Older TVs and players
How to open .webm files
| Platform | App | Notes |
|---|---|---|
| Browsers | Chrome, Safari, Firefox, Edge | Drag the file into a tab |
| Any system | VLC | Free |
| Windows | Media Player | Current versions |
Convert WebM files
From WebM
All 46 output formats: .mp4, .mkv, .avi, .mov, .gif, .m4v, .mpeg, .mpg, .ts, .m2ts, .mts, .m2v, .mxf, .ogv, .flv, .vob, .wmv, .asf, .divx, .3gp, .3g2, .ivf, .mp3, .wav, .m4a, .m4b, .ogg, .oga, .opus, .aac, .flac, .aiff, .aif, .wma, .ac3, .mka, .caf, .au, .tta, .wv, .mp2, .png, .jpg, .jpeg, .webp, .bmp
Conversions run in your browser. Files aren’t uploaded.
How to identify a .webm file
WebM is a subset of Matroska, so it starts with the same EBML bytes as MKV.
It’s read here, in your browser. Only the first bytes.
Your file
Questions about WebM
Is WebM better than MP4?
For the web it’s efficient and royalty-free. MP4 plays in more places.
Why does my screen recorder save WebM?
Browsers record to it natively.
Does converting WebM to MP4 lose quality?
A little, because VP9 usually has to be encoded again.
Can WebM have a transparent background?
Yes, with VP8 or VP9.