Convert a WebM file (web downloads, screen recordings) to a universally playable MP4 locally via re-encoding. No upload.
Running locally on your device ...
Running locally on your device ...
0%
Your files never left your device
No. Everything runs in your browser - your file never leaves your device. How this is verifiable
WebM is Google's open, royalty-free web video standard - no coincidence it is the output of many browser tools, including this very site's own screen- and webcam-recording tools. WebM is ideal for playback in a browser; for importing into video editors, sending via messenger apps, or playback on older devices, MP4 is often explicitly expected instead.
To be honest: unlike a MOV or MKV source, this conversion is almost never a plain repackage. WebM's codecs (VP8, VP9 or AV1 for picture, Opus or Vorbis for sound) never fit MP4's lossless copy set - the tool therefore practically always re-encodes the file via your browser's native hardware video encoder (WebCodecs).
Because your browser uses its own, usually hardware-accelerated encoder for this, the re-encode is still noticeably faster than a pure software encode - just not as instant as a repackage. Everything runs locally in the browser, with your video never uploaded.
| Input formats | WEBM |
|---|---|
| Auto-conversion | PNG, GIF, MP4 |
| Output format | MP4 |
| Batch processing | No |
| Processing | Locally in your browser (WebCodecs) |
| File upload | None |
Limitations: Since WebM's codecs never fit MP4's lossless copy set, this is practically always a real re-encode with minimal but measurable quality loss and unchanged resolution (for a different resolution/quality, use the sibling tool "Compress video"). One file per run, ~1 GB limit (4 GB/tab in the browser).
No, the entire conversion happens locally in your browser.
Because WebM's codecs (VP8/VP9/AV1) never fit MP4, a real re-encode is always needed, not a quick repackage.
Minimally, as with any re-encode - the chosen resolution stays unchanged, though.
From web downloads, screen recordings (e.g. the sibling "Screen recorder" tool) or browser-native recording tools.
Yes, use the sibling tool "Convert MP4 to WebM".