Convert WebM to MP4 in your browser
Turn WebM screen recordings and web downloads into MP4 files that play on any phone, TV or editor. Everything happens on your device.
How it works
- 1
Choose or drop the WebM file you want to convert.
- 2
Keep MP4 as the output format. The video becomes H.264 and the audio AAC.
- 3
Click WebM to MP4, then download the MP4 file. Nothing was uploaded.
Where WebM files come from
WebM is an open video format designed for the web. You typically get WebM files from browser-based screen recorders, from the recording feature of some video call and meeting tools, from OBS or other capture apps set to WebM, and from videos saved from websites.
Browsers play WebM without trouble, but plenty of other places do not: iPhone apps, older versions of QuickTime, many TVs, some social networks and a lot of video editors prefer or require MP4. Converting to MP4 is the simplest way to make the file usable everywhere.
What changes in the file
A WebM file holds VP9 or VP8 video (sometimes AV1) and Opus or Vorbis audio. MP4 files meant for maximum compatibility use H.264 video and AAC audio. Since these codecs are different, a WebM to MP4 conversion always re-encodes: the video is decoded and encoded again as H.264, and the audio is encoded to AAC.
Vidmini uses the browser’s WebCodecs API and your device’s hardware encoder when it is available, so re-encoding is usually fast. AAC is encoded natively or, on some browsers, with a WebAssembly encoder. The result is a standard MP4 file that plays in every player.
Screen recordings: sharp text, smooth playback
Screen recordings are often WebM because that is what browsers produce natively. They contain sharp text and large flat areas. Vidmini keeps the original resolution when converting, so text stays readable, and the result is a standard MP4 that editors and messaging apps accept.
If the recording is long, you can compress the MP4 or turn it into a GIF afterwards with "Continue with this file", without selecting the file again.
Private, offline-capable, no size limit set by us
The conversion runs entirely in your browser. Your WebM file is never uploaded, there is no account and no watermark, and the page keeps working offline once it has loaded.
We do not set a size limit: the MP4 is streamed into your browser’s private storage while it is being written, so desktop browsers handle files of several gigabytes. Phones are limited by their free memory and storage.
Frequently asked questions
Does converting WebM to MP4 reduce quality?
Any re-encoding changes the file slightly, but at the original resolution the difference is usually hard to see. The resolution stays the same as the source.
Why is WebM to MP4 slower than MOV to MP4?
WebM uses VP9 or VP8 video and Opus audio, which MP4 players rarely support. They have to be re-encoded to H.264 and AAC, whereas an H.264 MOV can simply be copied into MP4.
Can I play the MP4 on my iPhone?
Yes. H.264 video with AAC audio in an MP4 container is supported by iPhones, iPads, Macs, Android phones, Windows and virtually every TV and editing app.
Does it keep the audio of my screen recording?
Yes. The Opus or Vorbis audio track is converted to AAC and kept in sync with the video. If the recording has no sound, the MP4 has none either.
Which browsers can convert WebM?
The latest Chrome, Edge, Firefox and Safari, on desktop and mobile. Decoding VP9 or AV1 depends on your browser; Chrome and Edge have the widest codec support.
Is my video sent to a server?
No. The file is read and converted by your own browser. The page is only allowed to talk to vidmini.com for its own code, and it uses no tracking cookies.