Convert WEBM to MP4
Drop a WEBM file and get a broadly compatible H.264/MP4 back — playable on iOS, older Android, macOS, and every platform that expects MP4. The first time you use this tool the video engine downloads once (~26 MB); after that the browser uses its cached copy. Your file never leaves your device.
About WEBM to MP4
WEBM is an open, royalty-free format that plays natively in Chrome, Firefox, and Edge, but has limited support on iOS (before iOS 16), older Android devices, Windows Media Player, and many social platforms and messaging apps that only accept MP4. Converting to MP4 gives you a file that works everywhere.
The output uses H.264 video (Baseline profile, YUV 4:2:0) and AAC audio in an MP4 container. The moov atom is placed at the start of the file (“faststart”) so video players can begin playback immediately without reading the full file first. If the source WEBM has no audio track, the output will be video-only.
Is it private?
Yes. The converter is WebAssembly and browser APIs running on your own machine. Nothing is uploaded, stored, or seen by us — there is no server to send files to.
Frequently asked questions
- Why convert WEBM to MP4?
- WEBM plays natively in Chrome, Firefox, and Edge, but has limited support on iOS before iOS 16, older Android devices, Windows Media Player, and many social platforms and messaging apps that only accept MP4. Converting to MP4 gives you a file that works everywhere.
- What format does the MP4 output use?
- The output uses H.264 video (Baseline profile, YUV 4:2:0) and AAC audio in an MP4 container. The moov atom is placed at the start of the file (faststart) so players can begin playback immediately. If the source WEBM has no audio track, the output will be video-only.
- Are my files uploaded to a server?
- No. The conversion runs on your device using WebAssembly and browser APIs. Your video is never sent anywhere. The first time you use the tool the video engine downloads once (about 26 MB); after that the browser uses its cached copy.
- Is it free, and do I need an account?
- It is free with no watermarks, no daily caps, and no sign-up. Drop a file, convert it, and download the result.