WebM with VP9 encoding produces smaller files than H.264 MP4 at equivalent quality — making it ideal for web delivery. The HTML5 `<video>` element supports WebM in all modern browsers. If you're serving video on a website, WebM as a primary source with MP4 fallback is the recommended approach. Convert your MP4 clips to WebM here, in your browser, with no upload needed.
Drop files here
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Up to 500.0 MB per file
Upload your MP4 file
Drop an MP4 video file. Up to 500 MB supported. Note that VP9 encoding is computationally intensive — allow extra time for larger files.
Let FFmpeg encode
FFmpeg uses VP9 (libvpx-vp9) with CRF 30 and Opus audio. VP9 encoding is slower than H.264 but produces 20–40% smaller files at the same quality. Progress is shown in real time.
Download the WebM
The output WebM file is ready for web delivery. Use it as the primary `<source type="video/webm">` in an HTML `<video>` element, with an MP4 fallback for Safari.
Deploy to your website
WebM plays in Chrome, Firefox, and Edge. Use a `<picture>`-style approach with `<source>` elements to serve WebM to modern browsers and MP4 to Safari.
VP9 WebM is typically 20–40% smaller than H.264 MP4 at the same perceptual quality. For video-heavy websites, this can be significant — a 10 MB MP4 background video might become a 6 MB WebM. AV1 WebM is even more efficient but encoding is extremely slow in software, so we use VP9.
Safari on macOS 12.3+ and iOS 16+ added basic WebM support, but it's incomplete (VP8 only, not VP9). For universal compatibility, always provide an MP4 fallback. Use the HTML5 <video> element with two <source> tags: WebM first (for Chrome/Firefox), MP4 second (for Safari).
VP9 encoding is 3–5× slower than H.264 at comparable quality. A 1-minute MP4 that takes 30 seconds to re-encode as H.264 might take 2–3 minutes as VP9. This is inherent to the VP9 codec — it's a deliberate trade-off for better compression. AV1 is even slower. For large files, consider using a desktop tool like Handbrake.
Yes. Short WebM loops are ideal for web backgrounds — they load faster than MP4 equivalents. Use `autoplay muted loop playsinline` attributes on the `<video>` element. For cross-browser support, pair with an MP4: `<source src="bg.webm" type="video/webm"><source src="bg.mp4" type="video/mp4">`.
Opus audio at 128 kbps. Opus is the preferred audio codec for WebM — it outperforms Vorbis and is royalty-free. All browsers that support VP9 also support Opus, so there are no compatibility issues.
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