WebM with VP9 codec delivers outstanding video quality at low file sizes for the web. Convert any video to WebM for HTML5 video tags, YouTube uploads, browser-based playback, and progressive web apps.
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Up to 100 MB free • Outputs: WEBM
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Convert your files in three simple steps — no software, no signup.
Upload any video file in MP4, AVI, MKV, MOV, WMV, or any other supported format. Up to 500 MB is accepted.
Select the VP9 quality level (CRF) and target resolution. Lower CRF values produce larger, higher-quality files; higher values give compact, web-efficient files.
Download your WebM file ready to embed in HTML5 web pages or upload to any platform that accepts WebM video.
WebM was specifically designed for HTML5 web delivery. It streams efficiently, loads fast, and plays without plugins in Chrome, Firefox, Edge, and Opera.
VP9 provides 50% better compression than H.264 at equivalent quality, meaning smaller file sizes for faster web delivery without sacrificing clarity.
WebM and VP9 are open, royalty-free standards developed by Google. No licensing fees, no codec patents — truly free for web use.
YouTube serves most videos as WebM/VP9 to Chrome and Firefox users. Converting your content to WebM matches YouTube's own delivery format.
Drop the converted file directly into an HTML5 <code><video></code> tag or use it alongside MP4 as a fallback for maximum browser coverage.
All uploaded videos are processed in isolation and automatically deleted from our servers within one hour.
All the formats you need, all in one place.
| Format | Description | Extension | Best Used For |
|---|---|---|---|
| MP4 → WEBM | Convert MP4 to web-optimised WebM | .mp4 |
HTML5 websites, progressive web apps |
| AVI → WEBM | Convert legacy AVI to modern WebM | .avi |
Archiving old footage for web display |
| MKV → WEBM | Matroska to lightweight WebM | .mkv |
Streaming via browser, web video players |
| MOV → WEBM | Apple QuickTime to open WebM | .mov |
Cross-browser web video delivery |
| WMV → WEBM | Windows Media to WebM | .wmv |
Converting legacy corporate training videos |
| GIF → WEBM | Convert animated GIF to compact WebM | .gif |
Replacing heavy GIFs with tiny WebM video |
| FLV → WEBM | Flash video to modern WebM | .flv |
Modernising Flash-era embedded video |
<source> element — browsers will select the format they support. <video> HTML5 element: <video src="video.webm" controls></video>. For broad browser support, include both WebM and MP4 sources inside the element. From everyday users to professionals — see how people rely on this tool every day.
Embed WebM in <code><video></code> tags alongside MP4 for full browser coverage with the smallest possible file sizes.
Upload WebM/VP9 to YouTube — it matches YouTube's own delivery codec, reducing extra server-side transcoding overhead.
WebM is royalty-free and streams efficiently in Chrome on desktop and Android — the dominant PWA browser environment.
Convert animated GIFs to WebM with the <code>loop autoplay muted</code> video attributes — typically 10–50× smaller than the equivalent GIF.
Most modern LMS platforms support WebM video. Use VP9 WebM to reduce bandwidth costs for students watching on mobile.
WebM/VP9 carries no patent royalties — ideal for open-source software, non-profits, and projects that must avoid H.264 licensing.
See how we compare to desktop software and other online converters.
| Feature |
Our Tool TransmuteBox |
HandBrake | Other Online |
|---|---|---|---|
| Royalty-free codec (VP9) | Varies | ||
| Smaller than H.264 at equal quality | Varies | ||
| Native browser support (Chrome/Firefox) | |||
| HTML5 <video> compatible | |||
| Vorbis / Opus audio | |||
| No install required | |||
| Auto-delete uploaded files | Varies |
Built on industry-standard open-source tools for maximum quality and reliability.
WebM is Google's open-source video container format built specifically for the web. Combined with the VP9 codec, it offers compression rivalling H.265 — without any royalty fees. Here's why WebM matters and how to use it effectively.
WebM was released by Google in 2010 as a royalty-free alternative to MP4/H.264 for web video. The H.264 codec carried patent royalties, which made it problematic for open-source browsers like Firefox. WebM, using the VP8 (and later VP9) codec, is free to use for anyone.
Today, WebM/VP9 is the format YouTube uses to serve video to Chrome and Firefox users — meaning billions of daily video views are delivered in WebM without viewers knowing it.
WebM supports two video codecs: VP8 (legacy) and VP9 (current). VP9 is dramatically superior:
To serve WebM video with an MP4 fallback on your website, use the following HTML5 pattern:
<video controls width="800">\n <source src="video.webm" type="video/webm">\n <source src="video.mp4" type="video/mp4">\n Your browser does not support HTML5 video.\n</video>Browsers select the first format they support — Chrome and Firefox will serve WebM, while Safari falls back to MP4.
Animated GIFs are notoriously large. A 2-second GIF can easily be 5–15 MB. The same content as a WebM video is typically 50–100 KB — a 50–150× size reduction. Use this HTML to embed an auto-playing, looping, silent WebM as a GIF replacement:
<video autoplay loop muted playsinline>\n <source src="animation.webm" type="video/webm">\n</video>As a general guide for WebM/VP9 output sizes at 1080p:
These are significantly smaller than equivalent MP4/H.264 files at the same quality level.