WebM to MP4 Converter

Turn a browser recording or web video into an H.264 MP4 that opens on iPhones, Macs, and in any editor.

100% free
No signup needed
Browser-based

Why use Jupitrr's WebM to MP4 converter?

A real H.264 MP4

WebM video is re-encoded to H.264 with AAC audio, the combination iPhones, QuickTime, and editors expect.

Never uploaded

Your WebM file is converted inside your browser and never leaves your device.

Free, no watermark

No signup, no install, and nothing added to your file.

How it works

Choose a WebM file

Drop a WebM video up to 1 GB onto the converter, or pick it from your device.

Keep MP4 selected

MP4 is already selected. You can switch to another output format if you need one.

Convert and download

The video is converted in your browser. Preview the MP4 file, then download it.

What is a WebM to MP4 converter?

From a web format to the one everything plays.

WebM is an open video format built for the web. It usually holds VP8 or VP9 video with Opus or Vorbis audio, and it is what many browser-based screen recorders and web apps save. Chrome and Firefox play it, but iPhones, QuickTime, and many video editors do not handle it well.

Jupitrr's converter re-encodes the WebM video to H.264 and the audio to AAC inside an MP4 container. That takes longer than a simple repackage, because each frame is encoded again, but the result is a standard MP4 instead of a WebM stream renamed to .mp4.

When to reach for it

Browser screen recordings

Make a WebM capture playable on Macs, iPhones, and in presentations.

Editing in Premiere or Final Cut

Import footage into editors that do not accept WebM.

Posting to social media

Upload clips to platforms that prefer H.264 MP4.

Sending to clients

Share a video that opens with a double click on any computer.

Frequently asked questions

Why does WebM to MP4 take longer than other conversions?

WebM video is usually VP8 or VP9, which iPhones and most editors cannot play inside an MP4. The converter re-encodes it to H.264, frame by frame, on your device. Time depends on the video length and your computer speed.

Will the MP4 play on iPhone and QuickTime?

Yes. The output uses H.264 video with AAC audio, which iPhones, QuickTime, Windows, and Android all play. If your browser cannot encode AAC audio, the original Opus audio is kept instead, so use Chrome, Edge, or Safari for the most compatible file.

Does converting WebM to MP4 lose quality?

Re-encoding always changes the video slightly, but the converter uses a high bitrate so the difference is hard to see. The file can end up larger than the WebM because H.264 is less efficient than VP9.

Is my WebM file uploaded to a server?

No. The WebM file is read and converted by your browser on your device. It is never sent to Jupitrr, and closing or refreshing the tab clears the working files.

Is there a file size limit?

Files up to 1 GB can be converted. Larger files can run out of browser memory, so trim or compress very long recordings first.

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