Free browser tool

Free MP4 to WebM Converter

Convert MP4 to a compact WebM for your website. Pick a quality preset and a max resolution, and strip audio for autoplay hero videos. No upload, no sign-up, no watermark — everything runs privately in your browser.

No upload
No sign-up
No watermark
Muted autoplay mode

Quality

VP8 WebM — plays in every browser that supports WebM. Balanced is visually close to the source for screen recordings and product demos; Small is fine for background hero loops.

Max resolution

Audio

Audio is removed while “Optimize for web autoplay” is on.

Optimize for web autoplayRemoves the audio track. Browsers only autoplay muted video, so a hero or background clip has no use for audio and gets smaller without it. Use it with <video autoplay muted loop playsinline>.

Drop your video here

or click to browse — MP4, MOV, MKV, AVI, GIF → WebM

Your video never leaves your device — 100% private

How to convert MP4 to WebM online

Drop your video

Select or drag in an MP4, MOV, MKV, AVI or GIF. Processing is local — nothing is sent to a server.

Pick quality and resolution

Balanced is the sweet spot for most product demos. Cap the resolution at 720p for long clips and leave “Optimize for web autoplay” on to drop the audio.

Download WebM

Preview the result, compare the before → after size and click Download. Copy the HTML snippet to embed it with an MP4 fallback.

WebM for landing pages

WebM vs MP4 for websites

WebM is open and royalty-free, plays natively in Chrome, Firefox, Edge and Android, and is the conventional format for muted autoplay clips. MP4 plays everywhere and is still the right fallback — ship both.

Autoplay hero video checklist

Remove the audio track — browsers only autoplay muted video
Use <video autoplay muted loop playsinline>
List the WebM source first, MP4 second
Add a poster image so the first frame shows instantly
Keep hero clips under 15 seconds and 720p–1080p

Browser support

Chrome, Edge, Firefox, Opera and Android play WebM. Safari plays it from 14.1 on macOS 11.3+ and on recent iOS. Older Safari, some smart TVs and email clients need the MP4 fallback.

File size expectations

A 10-second 1080p screen recording at Balanced usually lands between 1 and 3 MB; muted and capped at 720p it often drops under 1 MB. Small is fine for blurred or background loops.

Frequently Asked Questions

How do I convert MP4 to WebM online for free?

Drop your MP4 (or MOV, MKV, AVI, GIF) into the converter, pick a quality preset and wait for the encode to finish. Everything runs locally in your browser with FFmpeg — no upload, no sign-up, no watermark. Click Download to save the .webm file.

Why use WebM on a website instead of MP4?

WebM is the open, royalty-free video format built for the web: Chrome, Firefox, Edge and Android play it natively, and a muted WebM is the standard choice for autoplaying hero and background clips. It also lets you cap the bitrate tightly for small files. Keep an MP4 fallback for browsers that cannot play it.

Does Safari play WebM?

Safari 14.1 and later on macOS 11.3+ plays WebM, and recent iOS versions do too. Older Safari versions and some smart-TV browsers do not, so list the WebM first in a <video> tag and add an MP4 <source> after it. The browser picks the first format it can play.

Is the output VP8 or VP9?

VP8. The encoder runs entirely inside your browser through FFmpeg WebAssembly, and the VP9 encoder is not stable in that environment, so this tool produces VP8 WebM. Every browser that plays WebM plays VP8, so playback is identical — the files are just somewhat larger than a VP9 encode would be. If you need the very smallest file, run ffmpeg with -c:v libvpx-vp9 on your own machine.

Why is the conversion slow?

The encoder runs single-threaded in WebAssembly, so a 1080p clip takes roughly as long as it lasts, and 4K sources take longer. Cap the resolution at 720p to speed it up, and keep the tab open until it finishes.

Is my video uploaded to a server?

No. The converter uses FFmpeg compiled to WebAssembly and runs entirely on your device. Nothing is uploaded. Screen Charm, the Mac screen recorder behind this tool, records product demos and exports 4K MP4 that you can convert to WebM here for the web.