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First run downloads FFmpeg (~25 MB) once in this browser. Need the reverse? Try /webm-to-mp4.

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MP4 to WebM converter online free

Convert MP4 to WebM online free. Free MP4 to WebM converter — turn MP4 into WebM for the web with adjustable quality, no server upload.

What is an MP4 to WebM converter?

An MP4 to WebM converter changes MP4 video into the open WebM format (usually VP8 video), which is popular for HTML5 sites and lightweight web embeds. People search convert MP4 to WebM, MP4 to WebM format, or MP4 in WebM when a page or CDN prefers WebM. This free tool runs locally with FFmpeg WebAssembly — no server upload.

MP4 to WebM converter features

Free online MP4 to WebM conversion — browser-based, privacy-first.

  • Convert MP4 to WebM online

    Upload an MP4 file and download a WebM video in your browser.

  • MP4 to WebM format

    Change MP4 to WebM format for sites and players that prefer WebM.

  • Web-ready VP8 output

    Encodes VP8 video (libvpx) with optional Vorbis audio in a .webm container.

  • Adjustable output quality

    Tune VP8 CRF to balance visual quality and WebM file size.

  • No server upload

    FFmpeg WebAssembly processes video on your device for better privacy.

How to convert MP4 to WebM

Convert MP4 to WebM format or convert MP4 in WebM in three steps.

  1. Upload MP4 file

    Drop or select your .mp4 video (up to 200 MB).

  2. Set quality (CRF)

    Keep the default CRF 30 for balanced quality, or lower CRF for sharper output.

  3. Convert and download

    Click Convert to WebM, then download the result.

Great for

Common MP4 to WebM conversion scenarios.

  • HTML5 and web embeds

    Serve WebM alongside MP4 for efficient browser playback.

  • Smaller web videos

    Re-encode MP4 as WebM when a site workflow expects .webm.

  • Open-format delivery

    Use royalty-free VP8 WebM for open-source and web projects.

  • Privacy-first conversion

    Convert locally without uploading clips to a third-party server.

Frequently Asked Questions

Quick answers about this tool—open a question to read more.