Browser edition: files stay on your device. Up to 100 MB total and 10 minutes. First use downloads a 32 MB engine. Some formats depend on codec support. Public-link downloading is not ready on this free deployment.
Convert MP4 to WebM
Convert MP4 to WebM online for free. Smart remux when possible, high-quality encoding when not.
How to convert MP4 to WebM
- Add your fileDrop it on the page, choose it from your device, or paste it with Ctrl+V.
- ConvertAdjust settings if you like, then press the button. You'll see live progress.
- Browser processing uses original files on your device. Public-link downloading is unavailable.
What happens to your file
MP4 files are common for sharing, uploading to social networks, playing on any device, but not every app or device opens them. WebM is the better choice for website video, HTML5 players, transparent overlays. All-in-One Saver converts MP4 to WebM with FFmpeg — real decoding and encoding, not a renamed file extension.
A real re-encode. MP4 usually contains H.264 or H.265 video with AAC audio, which WebM players can't decode, so All-in-One Saver re-encodes to VP9 video and Opus audio. "Balanced" is visually indistinguishable from the source for most videos; "High" uses a lower CRF for archiving; "Smaller file" trades a little sharpness for a much smaller file.
Settings
- Quality — High, Balanced, Smaller file. Balanced keeps the original streams when possible (no quality loss, very fast).
- Resolution — Same as source, 4K (2160p), 1440p, 1080p, 720p, 480p, 360p, 240p
- Audio bitrate — Auto · keep original if possible, 320 kbps · best, 256 kbps, 192 kbps · standard, 128 kbps · small, 96 kbps, 64 kbps · voice
MP4 vs WebM
| MP4 | WebM | |
|---|---|---|
| Full name | MPEG-4 Part 14 | WebM |
| Created by | ISO / MPEG, 2001 | Google, 2010 |
| Type | Video container | Video container |
| Typical contents | H.264 or H.265 video with AAC audio | VP8, VP9 or AV1 video with Opus or Vorbis audio |
| Best for | sharing, uploading to social networks, playing on any device | website video, HTML5 players, transparent overlays |
| Strength | Plays everywhere, including iPhone, Android, Windows and macOS | Royalty-free and built for the web |
| Weakness | Lossy: every re-encode loses a little quality | Weak support in older Apple software and many video editors |
About MP4
- Type
- MPEG-4 Part 14
- Contains
- H.264 or H.265 video with AAC audio
- Use
- sharing, uploading to social networks, playing on any device
About WebM
- Type
- WebM
- Contains
- VP8, VP9 or AV1 video with Opus or Vorbis audio
- Use
- website video, HTML5 players, transparent overlays
FAQ
Will converting MP4 to WebM reduce quality?
A small amount, because the video has to be re-encoded. With the default "Balanced" setting (H.264 CRF 23) the difference is not visible for most videos; choose "High" to minimize it.
How long does it take?
Re-encoding runs at roughly real-time or faster for 1080p video. You'll see live progress and the time remaining.
Can I convert several MP4 files at once?
Yes. Drop up to 10 files at a time — each one is converted in parallel and you can download them individually or all at once.
Is there a file size limit?
Convert and edit files on your device. The browser edition accepts up to 100 MB total, media up to 10 minutes and video up to 4K. Codec availability and device memory can limit individual jobs.
Is this MP4 to WebM converter free and safe?
Yes. There are no pop-ups, redirects or fake download buttons, and no software to install. Files are transferred over HTTPS, processed in isolated job folders and deleted automatically.