Free browser tool

Free MP4 to WebM Converter

Convert MP4 to a compact WebM for your website. Choose VP9 or VP8, set 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
VP9 and VP8

Codec

VP9 encoding in the browser is slow — roughly real-time or slower. For clips over a minute, pick 720p to keep it quick.

Quality

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 codec and quality

VP9 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

VP9 WebM is typically 20–40% smaller than H.264 MP4 at the same quality, supports transparency and uses open codecs. 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 VP9 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 VP9 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 VP9 or VP8 and 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 with VP9 is usually 20–40% smaller than H.264 MP4 at the same visual quality, so hero and background videos load faster and cost less bandwidth. VP9 also supports an alpha channel for transparent video, and the codecs are open and royalty-free. 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 with VP9, 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.

VP9 or VP8 — which should I pick?

VP9 produces smaller files at the same quality and is supported by every current browser, so it is the default. VP8 encodes several times faster and plays on very old Chrome, Firefox and Android builds, but the files are larger. Use VP8 only when encode time matters more than size.

Why is the conversion slow?

VP9 is a demanding codec and the encoder runs single-threaded in WebAssembly, so it typically takes about as long as the clip itself, sometimes longer for 1080p or 4K sources. Cap the resolution at 720p or switch to VP8 to speed it up. 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.