MP4 -> WEBM · Local tool
MP4 to WebM
Convert an MP4 to WebM, usually smaller at the same quality.
Last updated
How do I convert an MP4 to WebM?
Drop the MP4 onto filetity's converter and the picture is re-encoded to VP9 and the audio to Opus, which are the codecs a WebM carries, using the encoders your browser already ships. Nothing is uploaded. The usual reason to do this is size on the web: VP9 commonly delivers the same visible quality as H.264 in twenty to forty per cent fewer bytes, which matters on a page people open on mobile data. The trade is time, because VP9 is more expensive to encode than H.264, so this takes longer than the same job in the other direction and the page shows an estimate before you commit. Modern Safari plays VP9 and older versions do not, so for a public site it is worth serving both and letting the browser pick.
01 / Your device
the file stays here
02 / Browser memory
the work runs locally
03 / Back to you
saved on this device
When you would use this
Situations, not settings.
- A video on a page people load on mobile data
- VP9 commonly delivers the same visible quality in twenty to forty per cent fewer bytes than H.264, which is worth real money on a busy page.
- A background or hero video on a site
- Serve the WebM first and an MP4 as a fallback, which is what the source element exists for, and most visitors get the smaller file.
- Avoiding patent-encumbered codecs
- VP9 and Opus carry no licensing attached, which matters for some projects in a way it does not for others.
How it works / no cloud
A conversion engine, not an upload form.
The picture is re-encoded to VP9 and the audio to Opus, both with the encoders your browser already ships, because a WebM carries only those families. The bitrate target comes from the source rather than from a fixed table, so a video that was already efficiently encoded is not handed a larger budget than it needs.
- Offline ready
- Installable app
- No file limit queue
Straight answers
No accordion. Nothing hidden.
- Is it free?
- Yes, with no watermark and no page limit.
- Does it need an account?
- No. There is no account system.
- Is my file processed on my device?
- Yes. The file is read by your browser and never uploaded. There is no server to send it to.
- What formats are supported?
- MP4 in. WebM out, VP9 video and Opus audio.
- What are the limits?
- VP9 encoding is slower than H.264, so expect this to take longer than the same job in the other direction. Estimated size is shown before you start.
- Does it work on mobile?
- Yes, on any modern mobile browser. Large files are limited by the memory the phone gives the browser.
- Does it work offline?
- Yes, once the page has loaded. The tool keeps working with no network connection.
- Why would I want WebM instead of MP4?
- For the web, mostly. VP9 typically delivers the same visible quality as H.264 in noticeably fewer bytes, which matters when the video is on a page people load on mobile data, and the format has no patent licensing attached to it. For anything going to a phone or an editor, MP4 is still the right answer.
- How much smaller will it be?
- Commonly twenty to forty per cent for the same visible quality, though it depends heavily on the footage: detailed, grainy material saves less than flat animation or a screen recording. The page shows an estimate before you start and the real figure afterwards.
- Will Safari play it?
- Modern Safari plays VP9 in WebM, and older versions do not. If your audience includes people on old Apple hardware, serve both and let the browser choose with a source element, which is what the format was designed for.
- Why is this slower than the other direction?
- VP9 is more expensive to encode than H.264, which is the trade for the smaller output. Your device is doing that work rather than a server, so a long or high resolution video takes real minutes, and the page says so before you commit.
- Does it work for a video with no sound?
- Yes. A video with no audio track converts normally and comes out with no audio track, which is what a screen recording exported without sound should do. Nothing is invented to fill the gap.
Keep working locally
3 available · more coming