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MP4 to WEBM converter

Convert MP4 videos to WEBM without uploading them anywhere.

Runs in your browserNo sign-upNo watermark

Your files never leave your device.

Quick answer

To convert MP4 to WEBM, drop your video in and press Convert. It runs in your browser, so big files take a while on a phone: a laptop is much faster.

Drop files here

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How to convert MP4 to WEBM

  1. Drop your MP4 video onto the box, or press Choose files.
  2. Press Convert. The first time, your browser downloads the converter engine, then the video is converted in a progress bar you can watch.
  3. Download your WEBM file when it finishes, or all of them as a ZIP.

MP4 is the video format that works almost everywhere: phones, TVs, browsers and social apps. WEBM is an open video format made for the web. Browsers play it directly and files are small, but older TVs and some editors do not accept it.

Common questions

Why convert MP4 to WEBM?

WEBM files are small and play natively in web browsers, which makes them handy for putting video on a website.

Will the video quality drop?

Slightly, because the video is encoded again. We use a high-quality setting, so most people cannot tell. Keep the original in case you want to convert again.

Is my video uploaded anywhere?

No. The conversion happens inside your browser tab, so your video never leaves your device. We cannot see it or keep a copy.

Why is it slow?

Video is heavy work, and it is done by your own device, not a server. A laptop or desktop is many times faster than a phone, and short clips are quick. Close other tabs to help.

Why was the first conversion slow to start?

The first time you convert audio or video, your browser downloads the conversion engine (ffmpeg, about 30 MB) from a public CDN. After that it is cached, so the next ones start straight away. Your files are not part of that download.

How big a file can I convert?

Everything runs in your browser's memory, so the limit is your device. We suggest about 500 MB on a computer and 100 MB on a phone. Beyond that, the tab may slow down or run out of memory. A computer is much faster than a phone.