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MP4 to WebM Converter

Convert MP4 videos to open WebM (VP8 + Vorbis) for websites and HTML5 players. Private.

Free once a day, no account needed. One file up to 25 MB. Unlimited with Image & Media or All Tools.See plans
Your files never leave your device

How to convert MP4 to WebM

  1. 1

    Choose your MP4 files

    Click the upload area or drag files onto it. Nothing is uploaded — files are opened locally.

  2. 2

    Adjust the settings

    Pick quality, then press the convert button.

  3. 3

    Download the result

    Save each file individually or everything at once as a ZIP.

WebM is royalty-free and plays natively in every modern browser — a good choice for website backgrounds and self-hosted video. Encoding happens on your device, which can take a while for long videos.

Read the full guide with screenshots

What is MP4?

MP4 is the most widely supported video format, used by phones, cameras, YouTube and every social platform.

What is WebM?

WebM is an open web video format used by browsers and screen recorders. Many editors, phones and social platforms expect MP4 instead.

Is it private?

Yes. Unlike upload-based converters, ZapMorph processes files inside your browser tab, so the file stays on your device. It is never transmitted, stored or logged — close the tab and it’s gone.

Frequently asked questions

Is the mp4 to webm converter free?

Yes, once a day. Convert one file up to 25 MB a day without an account. A free account gets one run a day on any Pro tool with files up to 50 MB; Pro and Lifetime plans are unlimited.

Are my files uploaded to a server?

No. The conversion runs entirely in your browser, so your files never leave your device. We only count how many files you convert — never their names or contents.

What is the maximum file size?

Up to 25 MB per file without an account, 50 MB with a free account, and 1 GB on Pro. Very large files also depend on your device’s memory.

Can I convert multiple MP4 files at once?

Yes. Select several MP4 files at once — up to 5 on the free plan or 50 on Pro — and download all results in a single ZIP.

Does it work on Mac, Windows, iPhone and Android?

Yes. It works in any modern browser — Chrome, Edge, Firefox and Safari — on desktop and mobile, with nothing to install.

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