Convert MP4 to WebM format. Free, private, runs in your browser.
100% private — your files and text never leave your browser. All processing happens locally on your device.
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WebM is an open, royalty-free video format developed by Google. It uses the VP8 or VP9 video codec and the Vorbis or Opus audio codec. WebM is designed specifically for web use — it's supported by all modern browsers and offers efficient compression. Because it's open-source, there are no licensing fees for publishers.
WebM is the preferred format for web video when you want an open-source, royalty-free solution. Some open-source projects and platforms prefer WebM over MP4 (which uses the patent-encumbered H.264 codec). WebM also integrates well with the HTML5 video element and can deliver competitive quality at similar or smaller file sizes.
Convertful uses FFmpeg compiled to WebAssembly to decode your MP4 and re-encode it as a WebM file using the VP9 video codec. Audio is converted to Opus format. The entire conversion runs in your browser — no server, no upload, no waiting for cloud processing.
Yes. Your video never leaves your device. All processing happens locally in your browser.
WebM is an open video format optimized for the web. It's supported by all modern browsers and offers excellent compression with smaller file sizes.
You can convert MP4, MOV, AVI, MKV, WebM, and M4V files to WebM format. All processing happens in your browser using FFmpeg.
WebM uses VP8/VP9 codecs which provide excellent quality at smaller file sizes. Some minor quality differences are possible but are generally imperceptible.
Light preserves the most detail (libvpx CRF 24) and is best when the WebM will be edited again or shown on large displays. Standard (CRF 30) is the default and targets balanced file size for the web. Maximum (CRF 36) trades visible softening for noticeably smaller files — useful for background loops or preview clips where size matters most.