Slimvid

Preset · WebM to MP4 · stays on device

Convert WebM to MP4 Online

Turn browser recordings and VP8/VP9 WebM files into MP4 for iPhone, Premiere and chat apps.

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 .webm file from Chrome or your recorder.
  2. 2Leave MP4 selected.
  3. 3Convert and download a file iPhones and editors can open.

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.

WebM plays in Chrome. Not everywhere else.

Chrome, Meet and a lot of screen recorders save WebM (VP8/VP9/AV1). iPhone, Final Cut and Discord still prefer MP4.

This is almost always a transcode. VP9 inside WebM cannot be remuxed into MP4. The hardware encoder writes H.264.

Audio is usually Opus in WebM; we map it to AAC in the MP4 so Apple devices play sound.

What you get

Input
WebM (VP8 / VP9 / AV1)
Output
H.264 + AAC MP4
Typical source
Browser recordings

Three steps

How to convert WebM to MP4

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

  1. 1

    Drop your file

    Drop the .webm file from Chrome or your recorder.

  2. 2

    Choose settings

    Leave MP4 selected.

  3. 3

    Download

    Convert and download a file iPhones and editors can open.

Same job, other limits

Related size and platform pages

Convert MP4 to WebM OnlineMake a web-native WebM from an MP4 for HTML5 pages, Chrome recordings and lightweight embeds.MP4 → WebMConvert 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

WebM to MP4 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