MP4 to WebM Converter
Convert MP4 to WebM free — no upload, no signup
To convert MP4 to WebM, drop your MP4 video into the box below and click Convert. Fylo converts with ffmpeg running inside your browser, so nothing is uploaded and there's no signup or watermark. WebM uses royalty-free VP8 video and Vorbis audio for the web.
Drop videos here
or tap to browse · paste with Ctrl+V · add many at once
Your files never leave your device
If the video already uses codecs that fit the new format, Fylo repackages it instantly with no quality loss.
Advanced
How to convert MP4 to WebM
Add your MP4 videos
Drag and drop MP4 files into the box or tap to choose them. The converter engine (about 31 MB) downloads once, the first time you convert.
Choose quality (optional)
Balanced quality suits most videos. If the codecs already fit WebM, Fylo repackages the file instead of re-encoding it, with no quality loss.
Convert and download
Click Convert, then download each WebM file or all of them as one ZIP.
Why convert MP4 to WebM?
Web developers use WebM for HTML5 video on sites that want royalty-free codecs, and some platforms — such as certain game engines, sticker apps and Discord emotes — specifically ask for WebM.
What happens when you convert MP4 to WebM?
MP4's H.264 isn't allowed in WebM, so Fylo re-encodes video to VP8 using a fast real-time preset and audio to Vorbis. VP8 is less efficient than H.264, so the WebM may be somewhat larger at similar quality. Short clips convert in seconds; longer videos take a while because encoding happens on your device.
How does Fylo convert MP4 to WebM?
Fylo reads the MP4 with ffmpeg compiled to WebAssembly and writes VP8 with Vorbis audio, using libvpx's real-time preset so encoding stays practical in a browser. MP4's usual codecs (H.264, H.265/HEVC, AV1) can't go into WebM as-is, so the video is re-encoded. Speed depends on your device: short phone clips take seconds, while on our slow test PC a 2-minute 1080p video took about 10 minutes. Only the first video and audio track are kept, and the original resolution is preserved unless you pick 1080p, 720p or 480p under Advanced.
What's the difference between MP4 and WebM?
MP4 (MPEG-4 Part 14) is a container format standardised in 2001 and based on Apple's QuickTime file structure. A container holds separately compressed video and audio streams plus metadata such as subtitles, chapters and cover art. Most MP4s use H.264 video and AAC audio; newer files may use H.265 (HEVC) or AV1.
WebM was announced by Google in 2010 as an open, royalty-free alternative to H.264 for HTML5 video. It's a subset of Matroska restricted to VP8, VP9 or AV1 video and Vorbis or Opus audio. Browser screen recorders and many web tools save WebM by default.
Learn more: MP4 format guide · WebM format guide
| Property | MP4 | WebM |
|---|---|---|
| Developed by | MPEG (ISO/IEC 14496-14) | |
| Introduced | 2001 | 2010 |
| Typical video codecs | H.264, H.265/HEVC, AV1 | VP8, VP9, AV1 |
| Typical audio codecs | AAC, MP3 | Vorbis, Opus |
| Plays in web browsers | Yes — every browser | Yes — Chrome, Edge, Firefox, Safari 14.1+ |
| Compatibility | Universal: phones, TVs, editors, social media | Browsers, Android; limited in editors and on iPhone apps |
| Best for | Sharing, uploading, streaming, editing | Royalty-free web video, screen recordings |
Frequently asked questions
Why VP8 instead of VP9?
VP9 compresses better but is many times slower to encode in a browser. VP8 keeps conversion practical while staying fully WebM-compatible.
Do all browsers play WebM?
Chrome, Edge, Firefox and Safari 14.1+ do. For email or older devices, keep the MP4.
Is my MP4 file uploaded to a server?
No. Fylo runs ffmpeg, the same engine used by professional video tools, compiled to WebAssembly inside your browser. Your MP4 file is read directly from your device and never sent anywhere.
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