WebM to MP4 Converter

Convert WebM (.webm) to MP4 right in your browser. No upload.

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Connected — privacy mode available

You don't need the internet. Disconnect and watch the tool work.

Online

🔒 Verify the privacy claim yourself

Simplest way to confirm your videos never leave this device:

Disconnect from the internet.

Turn off your Wi-Fi → conversion keeps working. The banner up top turns green.

Note: a small one-time load happens on first use. After that, you can work fully offline.

or drop a WebM file here

Accepts WebM (.webm) — including clips downloaded from Twitter, Reddit, and other web sources

Output: MP4 container with H.264 video + AAC audio — the most compatible combination, playable everywhere from old phones to modern browsers.
Loading conversion engine (~30 MB) — first time only…

Why convert in your browser?

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Your video never leaves your computer

Conversion runs on your computer — not on someone else's server. Zero uploads.

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Lossless remux when possible

If your WebM file already contains H.264 video, we just rewrap it into an MP4 container — no re-encoding, no quality loss, near-instant.

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VP9 + VP8 source supported

Google's WebM codecs are transcoded to H.264 + AAC, making your clips playable on iOS, QuickTime, and any social app that rejects WebM.

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No watermark, no signup, no caps

CloudConvert caps free users at 10 conversions/day. Zamzar limits at 50 MB. VEED watermarks. We don't do any of that.

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No file size limit

Drop a 4 GB drone clip if you want. The only limit is your device's available memory — there's no upload step to choke on.

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Works offline after first visit

The engine downloads once, then runs forever. Turn off Wi-Fi to verify — conversion keeps working.

How we compare on "webm to mp4"

This tool CloudConvert Zamzar FreeConvert VEED.io
Video stays on your computer✓ VerifiableUploadsUploadsUploadsUploads
Free file-size capNone1 GB50 MB1 GB1 GB
Conversions per day (free)Unlimited10 / day2 / dayUnlimited—
Watermark on free tierNeverNoneNoneNone"VEED" on free
Lossless remux (H.264 source)✓ AutomaticRe-encodesRe-encodesRe-encodesRe-encodes
Signup requiredNeverNoFor >2 / dayNoFor pro

Common questions

Why won't my .webm play on iPhone or in QuickTime?

WebM uses VP8 or VP9 video codecs — Google's open formats — which Apple has historically refused to support. iOS Safari now plays VP9, but Photos, AirDrop, and most mobile editing apps don't. Converting to MP4 (H.264 + AAC) makes the file work everywhere.

How long does conversion take?

If your source already contains H.264 (older iPhones, most QuickTime recordings), conversion is a fast remux — usually under a second. HEVC is just as fast if you keep it as HEVC. Converting to H.264 re-encodes every frame and is much slower: on a recent Mac, a minute of 1080p HEVC takes about 4 minutes. 4K footage and older computers take longer.

Does my video get uploaded to your server?

No. Conversion runs entirely in your browser. Disconnect from Wi-Fi after the page loads to verify — the converter keeps working.

Is there a watermark or file-size limit?

Neither. Plain .mp4 output. No backend means no caps — the only limit is your device's available memory.

Will I lose quality?

If the source is H.264, or HEVC you choose to keep as HEVC, we remux (copy the video stream into MP4 without re-encoding) — 100% lossless. When we convert to H.264, we use CRF 18 by default, which is visually lossless for nearly all viewers.

Turn off your Wi-Fi. It still works.

That's how you know nothing leaves your computer.

CloudConvert, Zamzar, FreeConvert, VEED — they all send your video to a server. We don't. Conversion runs on your CPU, in your browser, via the same ffmpeg engine VLC and YouTube use.

Try it yourself ↑

Works on every device you use

iOS, Android, macOS, Windows, or any modern browser — same tool, same code, same privacy.

iOS
Android
macOS
Windows
Web