About this tool
WebM is the open format some websites, wikis, and open-source projects require for embedded video. This converter re-encodes MP4 (H.264) to VP8 video with Vorbis audio, which every modern browser plays natively.
About the formats: MP4 is the universal video container, usually holding H.264 video and AAC audio. It plays on every phone, browser, TV, and editing program, which is why most platforms ask for it. WebM is the open web video container (VP8, VP9, or AV1 video with Opus or Vorbis audio) produced by browser-based screen recorders and Chrome extensions. It works well in browsers, but iPhones, TVs, and most editing software will not open it.
MP4 and WebM, side by side
| .mp4 in | .webm out | |
|---|---|---|
| Usual codecs | H.264 video, AAC audio | VP8 or VP9, Vorbis or Opus |
| Plays on | Everything | Browsers, Android; Apple partly |
| Subtitles | Limited | WebVTT |
| Best for | Sharing and uploading | Web pages, screen recordings |
Rows where the two differ are marked. The full story on each: MP4 files and WebM files.
How to use it
- Drop your MP4, MOV or M4V files into the box above, or click to browse. Nothing is uploaded.
- Click Convert to WEBM and wait a moment.
- Download the results individually or all at once as a ZIP.
Questions
Why does MP4 to WebM take a while?
VP8 encoding is CPU-heavy and runs on one core in the browser. Short clips take a minute or two; long videos can take much longer.
Does WebM play on iPhone?
Safari on iOS 15 and later plays WebM in the browser, but the Photos app does not. Use MP4 for sharing with iPhone users.
Is it free, are files uploaded, which browsers work: the general questions are answered once for the whole site.