Convert MP4 Video to WebM

Convert MP4 video to WebM in your browser — a royalty-free format many sites prefer for embedded video.

Universal File Converter: Private & Fast

Convert images, videos, audio, and documents directly in your browser. Your files never leave your device, ensuring 100% privacy and security.

Video & Audio Converter

Extract audio from video or convert audio files between popular formats.

Drop your file here, or browse

Maximum file size: 50 MB

Supported: MP4, MOV, AVI, WEBM, MKV, MP3, WAV, FLAC, M4A, OGG

Output format

Advanced Media Tools

Extract Audio Trim Video

100% In-Browser Processing

Your files are processed strictly in local device memory. Nothing is uploaded — see how, and check for yourself.

How It Works

How to convert files with DuckConvert

Select Your File

Choose the file you want to convert from your device or drag and drop it into the converter.

Choose Output Format

Select your desired output format and any specific settings for your conversion.

Convert & Download

Click "Start Conversion" and wait for the local process to finish, then download your new file.

Don't take our word for it

This conversion runs entirely in your browser — nothing is uploaded. See exactly how, and check for yourself using your browser's DevTools Network tab.

How It Works

Conversion Mechanics

WebM is the format many self-hosted video setups and privacy-conscious sites default to, since it's built on royalty-free codecs and tends to produce smaller files than MP4 at similar quality. Converting your MP4 library to WebM is a common step when moving away from a third-party video embed toward hosting video yourself.

Why It's Private

Runs Entirely In Your Browser: Files are decoded and re-encoded strictly in local memory.
No Network Requests: The converter makes no calls to any server — check your browser's DevTools Network tab to confirm.
Nothing to Sign Up For: No account, no upload, and no server-side storage of your files.
Runs On Your Hardware: Processing uses your own device's CPU via Web Workers, not a remote server.

Step-by-Step MP4 to WEBM Local Guide

Select File

Drop your .mp4 file into the box above.

Configure

Confirm WebM is selected as the output format.

Convert

Click Convert — transcoding runs locally using an in-browser FFmpeg build.

Save Result

Download the resulting .webm file.

Frequently Asked Questions on Secure MP4 to WEBM Conversion

All current major browsers support WebM natively — it's one of the most widely supported web video formats.

It depends on the video's length, resolution, and your device's processing power — transcoding is CPU-intensive, so longer or higher-resolution videos take more time.

Yes, the audio track is transcoded along with the video rather than dropped.