WebM converter
Use an MP4 to WebM converter with no upload.
Convert an MP4 into a WebM file locally. Useful for web-first projects where WebM is the preferred delivery format.
MP4 to WebM converter
Browser-based WebM conversion for local MP4 files.
Your selected video is processed in this browser tab. It is not uploaded to a conversion server.
Ready.
A converter for browser-first video
This converter creates a WebM file from a selected MP4 while keeping the source video in the browser tab.
Best settings and limits
Best first try
Start with a short MP4. If you need the smallest file, inspect or compress after conversion and compare outputs.
When this may fail
Long videos can be slow because your device does the WebM encoding work locally.
Privacy boundary
The selected video file stays on your device while the tool creates the output.
Frequently asked questions
Is this an online upload converter?
No. The page loads online, but the selected video is processed locally in the browser.
Can Safari play WebM?
Modern browser support varies by device and version. Use MP4 when Safari compatibility is the main goal.
Can I convert WebM back to MP4?
Yes. Use the WebM to MP4 tool when MP4 compatibility is needed.