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MP4 ➝ WebM100% Client-Side
MP4WebM

MP4 to WebM Converter

Convert MP4 video into the web-friendly WebM container (VP9 + Opus) with WebAssembly ffmpeg — entirely in your browser.

Drop your MP4 file here, or browse

Drag & drop or click to select from your device

Maximum file size: 100 MB

How to

How to convert MP4 to WebM online for free

  1. 1Select or drop your MP4 file onto the converter — it stays in your browser.
  2. 2Adjust the optional settings, such as quality, size or output options.
  3. 3Click Convert — the file is processed locally on your device.
  4. 4Download your WebM file. It is ready in seconds.
FAQ

Frequently Asked Questions

Answers to the most common questions about Convrs.

How do I convert MP4 to WebM for free?
Select your MP4 file (or drag and drop it), click Convert and download the WebM result. There is no sign-up, no cost, and the file never leaves your browser.
Is MP4 ↔ WebM private and secure?
Yes. MP4 ↔ WebM runs entirely in your browser, so your data never leaves your device — nothing is uploaded or stored on a server. Video and audio tools use a WebAssembly engine that also runs in your device's memory.
Is WebM better than MP4?
WebM is an open, lightweight video format from Google — smaller files for the web. MP4 is the most widely compatible. Converting is useful when a site only accepts WebM.
What is the maximum file size?
100 MB per file. Because everything runs in your device's memory, very large files can slow down or freeze the browser.

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About this tool

MP4 → WebM: a complete walkthrough

MP4 ↔ WebM takes your MP4 and turns it into WebM — completely inside your browser. No install, no account, no watermark: you select or drop a file, review the settings, and download the result seconds later. Your files stay on your device.

Media files are the heaviest and most sensitive things you handle. Processing them in place means the audio or video never crosses the network: no upload progress bar, no server logs, no copy left behind — just the result on your device.

Privacy by construction: MP4 ↔ WebM runs entirely in your device's memory. Your files, text and data are never uploaded, stored or logged by us — there is no server in the path.

The heavy lifting uses WebAssembly: the same codec engines a desktop app would use are compiled to run inside your browser, so MP4 ↔ WebM delivers desktop-grade results while the file stays on your device.

Up to 100 MB per file
WebAssembly codec engine — desktop-grade processing in the browser
100% in-browser — nothing is uploaded
No account or sign-up required
Free to use, no watermarks
Runs on desktop and mobile browsers
Your source data is never stored or logged
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