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MP4 to WebM

Convert MP4 videos to WebM (VP9 + Opus) in your browser. No file uploads. Free and local.

How it works

  1. 1Choose a video from your device.
  2. 2Pick MP4, WebM, MOV or MKV as the output format.
  3. 3Convert the video, then download the result.

Other conversions

About this tool

Save a MP4 video as WebM with VP9 + Opus. Your file stays on your device. Only the primary video and audio tracks are kept. MP4 is a container, not an audio or video codec. A file may be silent or contain codecs your browser cannot decode. WebM output uses VP9 video and Opus audio. Check support in the target editor or player before replacing the original.

Choose a video and save it as MP4, WebM, MOV or MKV. Conversion runs on your device. Larger videos take longer and need more memory.

Questions

Which codecs and tracks does MP4 to WebM keep?

MP4 is a container, not an audio or video codec. A file may be silent or contain codecs your browser cannot decode. WebM output uses VP9 video and Opus audio. Check support in the target editor or player before replacing the original. Only the primary video and audio tracks are converted. Extra tracks and subtitles are not preserved. Unsupported source codecs produce an error.

Which video formats can I convert?

MP4, MOV, M4V, WebM, MKV and MPEG-TS use the browser media engine. AVI, WMV, FLV, 3GP, MPEG and other legacy containers use a separately downloaded converter. Codec support varies by browser; unreadable or unsupported videos show an error.

Which codecs do the output files use?

MP4, MOV and MKV use H.264 video and AAC audio. WebM uses VP9 video and Opus audio. Silent videos remain silent. Only the primary video and audio tracks are kept; subtitles and extra tracks are omitted.

Are videos uploaded to a server?

No. Files stay in your browser. Legacy formats download about 31 MB of converter code from jsDelivr the first time they are used, but your video is never sent there.

Does conversion improve quality?

No. Compatible video and audio tracks are copied where possible. Re-encoding can lose some quality and cannot restore detail missing from the source.

Can I cancel a conversion?

Yes. Use Cancel while conversion is running. Keep this tab open until you download the result. Very large files may exceed your browser's available memory.

docshift is a collection of free PDF, image, video, audio and data tools. File processing runs in your browser; files are never uploaded.

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