Free converter
MP4 to WEBM
Re-encode MP4 or MOV to WEBM with control over bitrate, resolution, frame rate and trim points. This is also the route to a smaller file. Because the conversion runs in your browser rather than on a server, your file is never uploaded, never stored and never seen by anyone else.
Drop your file to start.
The converter needs JavaScript, because the conversion itself runs on your own device rather than on a server. Enable JavaScript to load it.
Why WEBM
WEBM with VP9 is the format browsers can write natively, and it is well suited to the web: good quality per byte, universal browser support and no licensing complications. For a video going onto a website, it is usually the right container.
Expect real-time conversion
The clip plays once through a hidden canvas while the browser records the output, so conversion takes about as long as the video runs. Keep the tab in the foreground. Trimming to the section you actually need is the fastest way to shorten the wait.
How it works
- 1
Add your file
Drag it onto the drop zone, click to browse, or paste from the clipboard.
- 2
Confirm the format
WEBM is already selected. Open Settings if you want to adjust quality or size.
- 3
Download
Press Convert and save the result. Your file never leaves your device.
Frequently asked questions
Can I convert WEBM back to MP4?
Not here. Browsers cannot write MP4, so that conversion needs a server or desktop software such as HandBrake or FFmpeg.
Why does it take so long?
The conversion runs at playback speed because the video is captured as it plays. Trimming the clip shortens it; lowering the resolution does not.
Which browser should I use?
Chrome, Edge or Firefox. Safari's WEBM recording support is limited and the conversion may fail there.
Will the audio be kept?
Yes, unless you tick Remove audio in Settings. The audio track is captured alongside the video.