About this tool
Browser-based screen recorders and Chrome extensions save WebM, which iPhones, PowerPoint, and most editors will not open. WebM video (VP8/VP9) must be re-encoded to H.264 for MP4, so this one takes a little longer than a container swap, but the result plays everywhere.
About the formats: 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 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 and MP4, side by side
| .webm in | .mp4 out | |
|---|---|---|
| Usual codecs | VP8 or VP9, Vorbis or Opus | H.264 video, AAC audio |
| Plays on | Browsers, Android; Apple partly | Everything |
| Subtitles | WebVTT | Limited |
| Best for | Web pages, screen recordings | Sharing and uploading |
Rows where the two differ are marked. The full story on each: WebM files and MP4 files.
How to use it
- Drop your WebM files into the box above, or click to browse. Nothing is uploaded.
- Click Convert to MP4 and wait a moment.
- Download the results individually or all at once as a ZIP.
Questions
Why is WebM to MP4 slower than MOV to MP4?
MP4 cannot hold VP8/VP9 video, so every frame must be decoded and re-encoded as H.264. Expect roughly real-time speed for 720p and slower for 1080p.
Will the quality drop?
The re-encode uses a high quality setting; you should not notice a difference for screen recordings.
Is it free, are files uploaded, which browsers work: the general questions are answered once for the whole site.