MP4 to WebM Converter

Convert MP4 videos to WebM instantly and privately. Everything happens on your own device — nothing is uploaded to a server.

Drop your MP4 file here

Accepted: .mp4 · Max 300MB

Choose File

Files stay on your device — nothing is uploaded.

The video engine downloads once (about 30MB) the first time you convert, then stays cached in your browser for future conversions. Video encoding is CPU-intensive, so longer or higher-resolution clips take noticeably longer than audio extraction.

What is MP4 to WebM conversion?

MP4 to WebM conversion re-encodes your video's picture and sound into WebM, changing the container and codecs while keeping the same content. MP4 is the most widely supported video container format, typically pairing H.264 video with AAC audio. It's the default format for video recorded on phones and shared online. WebM is an open, royalty-free video container developed for the web, typically pairing VP8/VP9 video with Vorbis or Opus audio. It's built into every modern browser and favored for its smaller file sizes.

How to convert MP4 to WebM

Choose an MP4 file using the drop zone above (or drag and drop it in).
Wait a moment while your browser converts the file locally.
Click "Download" to save your new WebM file.

Why convert MP4 to WebM?

Converting between video formats is useful when a platform, editor, or device only accepts WebM, or when you want WebM's balance of compatibility and file size instead of MP4's.

MP4 vs WebM

Property	MP4	WebM
Compression	Lossy	Lossy
Typical use	Phone and camera video recordings	Embedded video on websites

Is this conversion private?

Yes. This MP4 to WebM converter runs entirely in your browser using a WebAssembly build of FFmpeg — your file is never uploaded to our servers, stored, or logged. Closing this tab discards everything.

Supported browsers

This converter works in all modern browsers, including Chrome, Firefox, Safari, and Edge, on both desktop and mobile (Android and iOS).

Frequently Asked Questions

How do I convert MP4 to WEBM?: Choose an MP4 file using the drop zone or "Choose File" button above. The converter runs in your browser using a WebAssembly build of FFmpeg and gives you a "Download" button for the resulting WEBM file — no upload, no waiting on a server.
Is this MP4 to WEBM converter free?: Yes. The converter is completely free with no sign-up, no watermark, and no limit on how many files you convert.
Are my files uploaded to a server?: No. This conversion happens entirely inside your browser using a WebAssembly build of FFmpeg. Your file is never uploaded, stored, or transmitted anywhere.
Does converting MP4 to WEBM reduce quality?: Re-encoding between video formats involves recompressing both picture and sound, so there's a small quality trade-off — but the default settings here stay close to the source while keeping in-browser conversion practical.
Can I use this converter on my phone?: Yes, but audio/video conversion is CPU-intensive. It will work on modern phones, though larger files may take noticeably longer than on desktop.
What is the maximum file size I can convert?: Because conversion happens on your own device, the limit depends on your browser and device memory. We recommend keeping individual files under 300MB, and a few minutes long, for the smoothest experience.

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What is MP4 to WebM conversion?

Property

MP4

WebM

Compression

Lossy

Typical use

Phone and camera video recordings

Embedded video on websites

Frequently Asked Questions

How do I convert MP4 to WEBM?

Choose an MP4 file using the drop zone or "Choose File" button above. The converter runs in your browser using a WebAssembly build of FFmpeg and gives you a "Download" button for the resulting WEBM file — no upload, no waiting on a server.

Is this MP4 to WEBM converter free?

Yes. The converter is completely free with no sign-up, no watermark, and no limit on how many files you convert.

Are my files uploaded to a server?

No. This conversion happens entirely inside your browser using a WebAssembly build of FFmpeg. Your file is never uploaded, stored, or transmitted anywhere.

Does converting MP4 to WEBM reduce quality?

Re-encoding between video formats involves recompressing both picture and sound, so there's a small quality trade-off — but the default settings here stay close to the source while keeping in-browser conversion practical.

Can I use this converter on my phone?

Yes, but audio/video conversion is CPU-intensive. It will work on modern phones, though larger files may take noticeably longer than on desktop.

What is the maximum file size I can convert?

Because conversion happens on your own device, the limit depends on your browser and device memory. We recommend keeping individual files under 300MB, and a few minutes long, for the smoothest experience.