WebM to MP4 Converter

Drop one or more WebM files and get MP4s that play on every phone, TV and editor. WebM uses VP8/VP9/AV1, so the video is re-encoded to H.264 with your hardware encoder for full compatibility.

How to use it

  1. Drop one or more WebM files, or click to choose them. MP4 is already selected as the target.
  2. Leave Maximum compatibility on so the file plays everywhere; only what is needed gets re-encoded.
  3. Click Start. Each file shows whether it was copied without re-encoding or re-encoded on this device.
  4. Download the MP4s one by one, or Download all.

Frequently asked questions

Does converting WebM to MP4 reduce quality?

If the WebM already contains H.264 video and AAC audio, the streams are copied into a new MP4 container without re-encoding — that takes seconds even for long recordings and loses no quality.

Is there a file size limit?

No fixed limit. The video is read in small slices and the result is streamed to your disk, so even multi-gigabyte files work without filling up memory.

Is my video uploaded to a server?

No. The file is read and written inside your browser tab using WebCodecs — nothing is uploaded, there is no account and no watermark. Once loaded, the page also works offline.