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Convert.mkv

Convert MKV to WebM online

100% localFiles never leave your device — no upload, no account, no tracking.
About MKV to WebM

Convert MKV (Matroska) videos into WebM, the open format that streams efficiently in browsers. We re-encode to VP9 at the quality you choose. VP9 encoding is thorough, so longer clips take a little time.

The transcode runs entirely in your browser via WebAssembly — FFmpeg compiled to WASM — so your MKV file is never uploaded to any server.

How it works
  1. 01

    Add an MKV

    Drop your MKV file onto the page or pick it from your device.

  2. 02

    Set quality

    Choose a CRF value for the VP9 output quality.

  3. 03

    Convert

    Click Convert to encode a WebM locally in your browser.

  4. 04

    Download

    Save the WebM file.

Features
VP9 outputgreat for webadjustable quality
Frequently asked
How does the MKV to WebM converter work?
Convert MKV (Matroska) videos into WebM, the open format that streams efficiently in browsers. We re-encode to VP9 at the quality you choose. VP9 encoding is thorough, so longer clips take a little time.
Are my files uploaded to a server?
No. Everything runs entirely in your browser using local JavaScript and WebAssembly. Your files never leave your device.
Does it cost anything or require an account?
No. The converter is free, needs no sign-up, and runs locally in your browser.
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