WebM plays in browsers but is rejected by many video editors, phones and social platforms. MP4 is accepted essentially everywhere.
The video is re-encoded to H.264 with AAC audio, which is the combination those tools expect.
Conversion runs on your device, so nothing is uploaded and there is no queue to wait in.
How to use it
Add your WebM file — typically a screen recording or a web download.
Press Convert to re-encode it to H.264 in an MP4 container.
Download a file that opens in editors and on phones.
Supported formats and limits
Input
WebM (VP8/VP9)
Output
MP4 (H.264)
Why convert
WebM plays in browsers but is refused by many editors and devices
Quality
Re-encoded at settings that keep the difference hard to see
Where it runs
In your browser; nothing uploaded
Not for: Keeping the smallest possible file — VP9 in WebM is often more efficient than H.264; convert only when you need compatibility.
Frequently asked questions
Are my files uploaded to a server?
No. This conversion runs entirely inside your browser using your own device’s processing power. The file never leaves your computer or phone, which is why it also works when your connection drops.
Why will not my editor accept WebM?
WebM uses VP8/VP9, which many editors never implemented. H.264 in an MP4 is the near-universal interchange format.
Does the file get bigger?
Often slightly, since VP9 compresses a little better than H.264 at the same quality. The compress tool can bring it back down to a size you choose.