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WebM to MP4 Converter

WebM files come out of browsers: screen recorders, Discord and Telegram clips, OBS browser captures, videos saved from the web. They play fine in Chrome — and then refuse to open in iMovie, Premiere, WhatsApp or on an iPhone. This converter re-encodes the VP8/VP9 video to H.264 MP4 using your device's hardware encoder, entirely in your browser, so nothing is uploaded and there is no queue.

  • No upload — files stay on your device
  • Works offline once loaded
  • Free forever, no signup, no watermark
Drop your {{ fromLabel }} file here, or tap to choose Converted to {{ toLabel }} on your device — nothing is uploaded
Reading the file…

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  • File {{ sourceSizeLabel }}
  • Duration {{ durationLabel }}
  • Resolution {{ resolutionLabel }}
  • Video codec {{ info.videoCodec || '—' }}

Instant conversion — the streams are copied, no re-encoding, no quality loss

This file needs a re-encode to become {{ toLabel }}. Your browser's hardware encoder does the work — expect roughly the video's playing time or less.

Heads up: this file is over 500 MB. It will still work — everything streams from disk — but a re-encode can take a while, especially on a phone.

{{ instant ? 'Copying streams into the new container…' : 'Re-encoding with your hardware encoder…' }} {{ progress }}%

Preview
  • Original {{ sourceSizeLabel }}
  • {{ toLabel }} file {{ resultSizeLabel }}

Video stream copied untouched — identical quality to the original.

The audio track used a codec this browser could not convert, so the output is silent.

How to use this tool

  1. Drop your WebM file

    Screen recording, saved clip, OBS capture — the tool reads its codec, duration and resolution before doing anything.

  2. Convert to MP4

    VP8/VP9 video is re-encoded to H.264 on your own hardware — roughly the clip's playing time or faster. The resolution and frame rate stay exactly as they were.

  3. Download and use anywhere

    The MP4 opens in every editor, sends on WhatsApp, and plays on iPhones and TVs that rejected the WebM.

Questions people ask

Where did this WebM file even come from?

WebM is the web's native video format — browser-based screen recorders, Chrome extensions, Discord clips and many "save video" buttons produce it. It is excellent for the web and poorly supported everywhere else, which is why you are here.

Why won't WebM play on my iPhone or in my editor?

WebM uses the VP8/VP9 codecs, which Apple devices and most editing software either don't support or support only partially. MP4 with H.264 is the one combination that plays essentially everywhere, so that is exactly what this tool outputs.

Does converting WebM to MP4 lose quality?

This conversion is a real re-encode (VP8/VP9 and H.264 are different codecs, so a pure container swap is not possible), which costs a small, usually invisible amount of quality. Resolution and frame rate are preserved exactly — this is a format change, not a compression pass.

Is my video uploaded to a server?

No. The re-encode runs on your own device's hardware encoder via WebCodecs — the same chip your camera app uses. There is no upload, no queue, and the file never leaves your machine.

Which browsers can do this?

Chrome and Edge (desktop and Android) have the H.264 encoder this needs. Firefox and older Safari may not — the tool checks first and tells you plainly instead of spinning forever.

How long does the conversion take?

Hardware encoding typically runs at or above real-time speed: a 2-minute clip takes around a minute or two on a laptop, often much less. Long screen recordings are the slowest case — but there is still no upload time on top.

Related tools

Free because it costs us nothing to run: your browser does the work, not our servers. Made by Dynamb Technologies — we build software for businesses.