Convert MP4 to WEBM
Drop an MP4 and get a WEBM back — the open, royalty-free web video format. This is a full re-encode using VP9 video and Opus audio, so it may take a bit longer than a simple remux. The first time you use this tool the video engine downloads once (~26 MB); after that the browser uses its cached copy. Your file never leaves your device.
About MP4 to WEBM
WEBM is an open container format built around VP8/VP9 video and Vorbis/Opus audio. It is royalty-free, natively supported by Chrome, Firefox, and Edge, and is the preferred format for the HTML5 <video> element on the web. This converter outputs VP9 video and Opus audio, which gives better compression than the older VP8 codec.
Because VP9 encoding in a browser is computationally intensive, this converter uses speed-optimised settings (real-time mode) that trade some quality for a reasonable encode time. For very long or high-resolution clips, the conversion may still take a noticeable amount of time — this is expected and not an error.
Is it private?
Yes. The converter is WebAssembly and browser APIs running on your own machine. Nothing is uploaded, stored, or seen by us — there is no server to send files to.
Frequently asked questions
- Which codecs does the WEBM output use?
- The converter outputs VP9 video and Opus audio inside a WEBM container. VP9 gives better compression than the older VP8 codec, and the format is royalty-free and natively supported by Chrome, Firefox, and Edge.
- Why does the conversion take a while?
- This is a full re-encode rather than a simple remux, and VP9 encoding in a browser is computationally intensive. The tool uses speed-optimised real-time settings, but long or high-resolution clips can still take a noticeable amount of time, which is expected and not an error.
- Are my files uploaded to a server?
- No. The conversion runs on your device using WebAssembly and browser APIs, so your video is never sent anywhere. The first time you use the tool the video engine downloads once (about 26 MB), after which the browser uses its cached copy.
- Is it free, and do I need an account?
- It is free with no watermarks, no daily caps, and no sign-up. Drop a file, convert it, and download the result.