Slimvid

Preset · MP4 to WebM · stays on device

Convert MP4 to WebM Online

Make a web-native WebM from an MP4 for HTML5 pages, Chrome recordings and lightweight embeds.

Drop videos here, or click to browse

Up to 1GB each · MP4, MOV, WebM, MKV, AVI, WMV and 30+ more

Choose files

Processed locally in your browser. Nothing is uploaded.

Settings

Add a video and the settings for this tool appear here.

How it works

  1. 1Drop the .mp4 file.
  2. 2WebM is preselected on this page.
  3. 3Convert and download. Use MP4 instead if you need iPhone playback.

Processed locally in your browser. Nothing is uploaded.

Processed locally in your browser. Files never leave your device. Up to 1GB — larger files go to the desktop app.

When WebM is the right container

Some sites, Chrome Web Store listings and HTML5 players still want WebM. An MP4 will play in most browsers; WebM can be smaller with VP8/VP9.

If the source is already VP8/VP9, we remux. H.264 MP4 is transcoded into a WebM the browser can record-style play back.

Safari support for WebM is better than it used to be but still spotty. Keep an MP4 around if you need Apple devices.

What you get

Input
MP4
Output
WebM
Safari
Keep MP4 as a fallback

Three steps

How to convert MP4 to WebM

No sign-up, no upload queue, no watermark. Everything happens on your device.

  1. 1

    Drop your file

    Drop the .mp4 file.

  2. 2

    Choose settings

    WebM is preselected on this page.

  3. 3

    Download

    Convert and download. Use MP4 instead if you need iPhone playback.

Same job, other limits

Related size and platform pages

Convert WebM to MP4 OnlineTurn browser recordings and VP8/VP9 WebM files into MP4 for iPhone, Premiere and chat apps.WebM → MP4Convert MOV to MP4 OnlineTurn iPhone and camera MOV files into an MP4 that actually plays in browsers, Discord and slides.MOV → MP4Convert MKV to MP4 OnlineRemux a downloaded MKV into MP4 so phones, editors and chat apps will play it.MKV → MP4Convert AVI to MP4 OnlineTurn old camera and screen-recorder AVI files into an MP4 that phones and browsers can play.AVI → MP4

Keep going

Related tools

FAQ

MP4 to WebM FAQ

Desktop app

Files over 1GB? Take it to the desktop.

The browser version is perfect for everyday clips. When you need to crunch big footage or dozens of files, the desktop app does it faster on your own hardware.

Get early accessCompare web vs desktop
  • No file size limit — 4K, hour-long recordings, anything
  • Batch queues: drop a folder, apply one preset
  • Hardware-accelerated encoding (H.264 / H.265)
  • Works fully offline, same privacy guarantee