MP4 to WebM Converter — Free & Private
WebM is the open, royalty-free video format built for the web. Convert your MP4 to VP9 WebM for HTML5 <video> embeds, website background loops, open-source projects, and transparent video overlays. No upload, no server, no license fees.
Why Web Developers Choose WebM Over MP4
MP4 (H.264) is everywhere, but it carries patent licensing obligations — every encoder and decoder technically owes royalties to MPEG-LA. For open-source software, government websites, and organizations committed to open standards, this is a real legal constraint. WebM, developed by Google and released in 2010, uses the VP8 and VP9 codecs under a royalty-free license — anyone can encode, decode, and distribute WebM without owing licensing fees. Beyond licensing, WebM has a unique technical capability: VP8 and VP9 support alpha channel transparency, enabling video overlays with no background. H.264 MP4 simply cannot do this. For web background video loops, WebM + MP4 dual-source is the professional standard for full browser compatibility.
- 🆓 Royalty-free format — VP9/VP8 are patent-free; H.264 carries MPEG-LA licensing obligations
- 📉 30–40% smaller files — VP9 achieves better compression than H.264 at equal quality
- 🔲 Transparency support — WebM supports alpha channel video; MP4/H.264 does not
- 🌐 Universal browser support — Chrome, Firefox, Edge, Opera, and Safari 14+ all support WebM
- 💻 HTML5 video best practice — dual-source WebM + MP4 gives 100% cross-browser coverage
- 🔒 100% private — FFmpeg.wasm converts in your browser; no video data touches a server
How to Convert MP4 to WebM
Click "Convert Now" to open the video converter with MP4 → WebM pre-selected.
Drag & drop your MP4 or click Browse. Supports any H.264 or H.265 MP4 file.
FFmpeg.wasm re-encodes your video to VP8 or VP9 with Opus audio, entirely in your browser.
Your WebM file downloads automatically — ready to embed in your website or project.
Features
100% Private
FFmpeg.wasm runs locally. Your video files never leave your device.
Alpha Channel
Create transparent WebM video for web overlays — impossible with H.264.
Free Forever
No account, no fee, no watermarks. Royalty-free output included.
Smaller Files
VP9 encoding produces 30–40% smaller files than H.264 at equal quality.
Web-Ready
Output is optimized for HTML5 video embedding and autoplay background loops.
Opus Audio
Audio converts to Opus codec — WebM's royalty-free, high-quality audio standard.
Frequently Asked Questions
<source src="video.webm"> <source src="video.mp4">.