Made Good Designs

WebM to MP4

Convert WebM to MP4 online for free — turn WebM screen recordings, downloads and browser captures into MP4 with H.264 video and AAC audio that plays on iPhone, Windows, PowerPoint and every editor. Runs privately in your browser using hardware encoding.

100% private — your video is processed on your device, never uploaded. Conversion happens on your device; nothing is uploaded.

100% private — runs in your browser

Processing uses your browser’s built-in video encoders (WebCodecs) through the open-source Mediabunny library — your video is never uploaded. Works best in recent Chrome, Edge and Safari; the output is kept in memory, so very large files (several GB) may need a computer with plenty of RAM.

How to convert WebM to MP4

  1. Drop your WebM file in the box.
  2. Click Convert to MP4.
  3. Preview the MP4.
  4. Download it.

What you can use it for

  • Play browser and OBS recordings on any device
  • Import WebM clips into Premiere, Final Cut or PowerPoint
  • Share recordings on iPhone and WhatsApp
  • Upload to sites that only accept MP4

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Frequently asked questions

Why convert WebM to MP4?

WebM (VP8/VP9 + Opus) is great on the web but not supported by many phones, editors and Office apps. MP4 with H.264 plays everywhere.

Does it keep the audio?

Yes — Opus or Vorbis audio is converted to AAC. If your browser can't encode AAC, you'll be told and the video is kept without audio.

Is my video uploaded?

No. The video is read and encoded by your own browser using its built-in video encoders, so it never leaves your device — even large or private videos stay private.

Is there a file size limit?

There's no upload limit. The finished video is held in memory before download, so files up to a few GB work on most computers; very large files need more RAM.

Which browsers work?

Recent Chrome, Edge and Safari work best (they have hardware video encoders). Firefox 130+ works for most files.