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Convert WebM Video to MP4 That Plays Anywhere

Convert a WebM video to an H.264 MP4 that plays everywhere — in your browser.

Most tools run entirely on your device

Select a video file

WebM (VP8/VP9) — converted to H.264 MP4 in your browser

Click to choose, or drop a file here

You can also paste (Ctrl+V / Cmd+V)

Most tools run entirely on your device

About converting WebM to MP4

WebM is common from screen recorders and some web video sources, but MP4 remains the format with the broadest support across devices, editors and platforms — converting to MP4 is usually about that compatibility, not quality.

The video is decoded and re-encoded as MP4 using WebCodecs, the browser's native hardware-accelerated video codec API — entirely in your browser, with no upload of the video file involved.

Supported files

Accepts WebM video. Produces an .mp4 file.

Is my file uploaded?

No. Re-encoding happens entirely in your browser with WebCodecs — the video is never uploaded.

How to WebM to MP4

  1. 1

    Add your WebM

    Drop in the .webm file — it's read in your browser.

  2. 2

    Convert

    Click Convert to MP4; the video is decoded and re-encoded as H.264/AAC with the WebCodecs API.

  3. 3

    Download

    Save the MP4 — it plays on iPhone, in Premiere, on social media, everywhere.

WebM to MP4 — frequently asked questions

Is my file uploaded?+

No. The WebM is decoded and re-encoded to MP4 entirely in your browser with the WebCodecs API.

Why convert WebM to MP4?+

WebM (VP8/VP9) doesn't play on iPhones, in most video editors, or on some social platforms. H.264 MP4 plays essentially everywhere.

Is quality lost?+

It's a re-encode, so there's a small generational loss. At the default quality it's hard to notice; the file size is usually similar or a little larger.

Which browsers work?+

Chrome, Edge and Safari 17+. The tool tells you if your browser can't encode H.264.

Do you upload my files to a server?+

No — every tool here processes your files entirely on your device, and nothing is uploaded to a server. The only exception is the AI tools, which send the extracted text (not the file) to Claude to do their work.

Is there a file size limit?+

There's no artificial limit we impose, but since processing happens in your browser, very large files (500+ MB or 1,000+ pages) are limited by your device's memory rather than by us.