WebM to MP4

WebM doesn’t play in iOS Safari or in most video editors. MP4 plays everywhere. Drop a .webm to convert.

drop a video here

or click to choose

Why convert WebM to MP4?

WebM is Google's open video container, holding VP8/VP9/AV1 video and Vorbis/Opus audio. It's great on YouTube and Chrome, but it's a problem everywhere else: iOS Safari won't play it natively, most video editors don't import it, and most social-media uploaders reject it.

Converting WebM to MP4 re-encodes the video into H.264, which is the universal video codec. The output works in iMovie, Premiere, Final Cut, on iPhones, on smart TVs, and as Twitter/Discord/Reddit attachments.

How this tool works

Your .webm file is decoded, re-encoded to H.264 at your chosen quality, and packaged into an .mp4 container with AAC audio. The result plays anywhere.

FAQ

Does WebM ever play on iPhone?

No, not natively. Safari on iOS does not include a WebM decoder. You need to convert before sharing or viewing.

Is MP4 bigger than WebM?

Slightly, at the same visual quality. WebM (especially VP9 / AV1) is more efficient than H.264. The tradeoff is universality.

Does the file get uploaded anywhere?

No. Open this page, turn off your wifi, then try a file — it still works. That's the test.

What's the maximum file size?

Browser memory is the limit. WebAssembly caps at 2–4 GB per file. Most laptops handle 1080p videos under a gigabyte comfortably.

Why is it slow on my phone?

FFmpeg-WASM runs on your CPU, not hardware video encoders. Phones have less CPU, so encoding takes longer.

Can I cancel mid-encode?

Yes. The Cancel button terminates the worker immediately. You'll wait a few seconds the next time you start.