Convert MP4 to WEBM, Free
Upload your MP4 file and get a WEBM in seconds. No account, no watermark.
How to convert MP4 to WEBM
WebM is an open-standard video format developed by Google, specifically designed for streaming on the web. It uses the VP8 or VP9 video codec and Vorbis or Opus audio codec, and it is natively supported by all modern browsers without a plugin. Converting MP4 to WebM is essential when you want to embed video directly in a web page using the HTML5 <video> element for maximum browser compatibility, or when you need a format that supports alpha (transparent) video.
BoltConverter re-encodes your MP4 video as WebM on our servers using VP9, which provides excellent compression and quality for web delivery. After conversion, both files are deleted from the server immediately.
Upload your MP4 file
Click the upload area or drag your .mp4 file onto the page.
Video is re-encoded as WebM/VP9
BoltConverter re-encodes the video using the VP9 codec inside a WebM container on our servers.
Download the WebM file
Click Download to save the WebM file for use on your website or web application.
Frequently asked questions
Why use WebM instead of MP4 for web video?
WebM is royalty-free and natively supported by all modern browsers including Chrome, Firefox, and Edge without any license fees. MP4 with H.264 is also widely supported, so offering both formats in an HTML5 video element ensures maximum compatibility.
Does WebM support transparency (alpha channel)?
Yes. VP9 in a WebM container supports alpha transparency, which MP4 with H.264 does not. This is one of the key reasons to use WebM for overlay videos and graphics with transparent backgrounds.
Will there be quality loss when converting MP4 to WebM?
Yes. This is a transcode from H.264 to VP9, both lossy codecs, so there is a small quality reduction. BoltConverter uses a high-quality VP9 encoding setting to keep any degradation imperceptible.
Is there a file size limit?
MP4 files up to 500 MB are supported. WebM encoding is computationally intensive, so larger files may take several minutes.
Are my files stored after conversion?
No. Both the uploaded MP4 and the resulting WebM are deleted from our servers immediately after you download the result.