Does MP4 to WebM reduce quality?

The video is re-encoded to VP9. At the same file size VP9 usually looks as good as or better than H.264.

What happens to the audio?

The AAC audio is converted to Opus, which is what WebM uses.

Is there a file size limit?

Browsers handle roughly 1 GB in memory. Because VP9 is slow, files under a few hundred megabytes and 1080p are the practical range.

Is it free and private?

Yes. No sign-up, no watermark, and the file never leaves your device.

Free · No sign-up

MP4 to WebM

Turn an MP4 into a lean VP9 WebM for your website or Discord – no upload, no sign-up, no watermark added.

AI · Paid creditsAI Video Watermark Remover AI Video Eraser

No upload
No sign-up
No new watermark
MP4, MOV, WebM, MKV, AVI

Drop a video here or click to choose

MP4, MOV, WebM, MKV, AVI · best under 300 MB

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A real input to try

Start with an openly licensed sample.

An 8-second blue-mug MP4, shared by the remove-ai-watermarks project under Apache-2.0. The source maintainer documents Google Flow / Veo 3.1 Fast. Use the unchanged original to try this editing tool.

Input · video/mp4

This card shows an input, not a processed result. Loading it does not upload it or start a paid task.

Source: wiltodelta · Apache-2.0
Input: 1280 × 720 · 0.90 MiB

Attribution and modifications · Media facts and hashes

WebM is the open video format built for the web. It uses VP9 video with Opus audio, plays natively in Chrome, Firefox and Edge, and usually comes out smaller than the equivalent MP4. Web developers use it for background videos; Discord users use it to fit under the size limit.

This converter re-encodes your MP4 into a WebM. Drop the file in and click Convert. The result is ready for a <video> tag or a chat post.

The encoding runs in your browser with FFmpeg WebAssembly. Nothing is sent to a server, no account is needed, and no watermark is added.

VP9 is slow to encode

VP9 takes several times longer than H.264. Keep clips short and under 1080p for a reasonable wait.

Keep the MP4 as a fallback

Safari on older iPhones does not play WebM. On a website, list the WebM source first and the MP4 second so every browser has an option.

Discord limit

Combine this converter with the video compressor to get a clip under 10 MB. Convert first, then compress if it is still too large.

All tools

A place for every edit.

Remove a logo, refine your footage, change a format or take the sound with you. Find the tool for your next step.

15 tools

Watermark removal

Start with the part you want to remove.

10 tools

Edit video

Shape the frame, timing and movement.

7 tools

Convert

Get the format your next step needs.

3 tools

Audio

Keep the sound, without the video.