Choose a WebM video.
Files stay on your device
WebM to MP4 Converter
Create a broadly compatible MP4 without uploading your video. Codec support is checked before conversion.
Private browser workspaceInput: WebM → Output: MP4
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Your file never leaves this browser
Processing happens locally using browser APIs and on-device code. Closing this tab clears the working data.
How it works01 02 03
Done in three simple steps
Check browser codec support.
Convert, preview, and download the MP4.
Frequently asked questions
Are my files uploaded?+
No. Your files stay on your device and are processed locally by your browser.
Which browsers work best?+
Recent Chromium browsers generally provide the broadest WebCodecs support. We check before starting.