Are my MP4 files uploaded anywhere?

No. This conversion runs entirely inside your browser, so the file never leaves your device. You can confirm it yourself: open the network tab of your browser's developer tools and convert something. You will see the page load, plus the analytics and advertising the site is paid for with — and nothing carrying your file.

Is converting MP4 to WebM free?

Yes. There is no account, no watermark and no limit on how many files you convert — it runs on your own machine, so it costs us nothing to let you. Files up to 100 MB are handled in the browser.

Does converting MP4 to WebM lose quality?

WebM is a compressed format, so some data is discarded. At the default setting the difference is not visible; you can raise the quality setting if you need to be certain. Video is re-encoded rather than copied, so some detail is lost even at the highest setting. Subtitle tracks and chapters are not carried over.

Do I need to install anything to open WebM files?

No installation is needed for the conversion itself — it runs in the browser you already have. Opening the WebM afterwards needs whatever software normally handles WebM Video on your device.

MP4toWebM

Convert MP4 to WebM

Up to 100 files at once. Mixed formats are fine.

You can convert MP4 to WebM free and without an account: drop the file above and the WebM is ready to download in a second or two. The conversion happens inside your own browser, so the file is never uploaded — it works on Windows, Mac, Linux, iPhone and Android, and keeps working with the network switched off.

What MP4 and WebM are for

The video format that plays everywhere. If in doubt, this is the answer.

The royalty-free web video format. Small files, plays in browsers, ignored by most TVs.

How to convert MP4 to WebM

Drop your MP4 file onto this page, or click to pick one.
Choose WebM as the target. The conversion runs inside your browser — the file is never uploaded.
Download the finished WebM file.

MP4 vs WebM: what changes

MP4 compared with WebM
	MP4	WebM
Full name	MPEG-4 Video	WebM Video
File extension	.mp4	.webm
Media type	video/mp4	video/webm
Compression	Lossy — file size is bought with quality	Lossy — file size is bought with quality

Quality: Some quality is given up for a smaller file. At the default setting the difference is hard to see.
Where it runs: This conversion runs inside your browser. Your file is never uploaded, and it works with the network disconnected.
What can be lost: Video is re-encoded rather than copied, so some detail is lost even at the highest setting. Subtitle tracks and chapters are not carried over.

MP4 to WebM: common questions

Are my MP4 files uploaded anywhere?: No. This conversion runs entirely inside your browser, so the file never leaves your device. You can confirm it yourself: open the network tab of your browser's developer tools and convert something. You will see the page load, plus the analytics and advertising the site is paid for with — and nothing carrying your file.
Is converting MP4 to WebM free?: Yes. There is no account, no watermark and no limit on how many files you convert — it runs on your own machine, so it costs us nothing to let you. Files up to 100 MB are handled in the browser.
Does converting MP4 to WebM lose quality?: WebM is a compressed format, so some data is discarded. At the default setting the difference is not visible; you can raise the quality setting if you need to be certain. Video is re-encoded rather than copied, so some detail is lost even at the highest setting. Subtitle tracks and chapters are not carried over.
Do I need to install anything to open WebM files?: No installation is needed for the conversion itself — it runs in the browser you already have. Opening the WebM afterwards needs whatever software normally handles WebM Video on your device.