MP4 to WebM
VP8 video with Opus audio, in a patent-free container.
Your file
Drop a file here, or click to choose
It stays on this device. Nothing is sent anywhere.
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Why WebM
WebM is the open, royalty-free video format. If you are shipping video inside a product, or serving it from a page where you would rather not think about h.264 licensing, WebM is the format that avoids the question entirely. Every current browser plays it, including Safari from version 14 onward.
VP8, not VP9
Two codecs can live in a WebM file. VP9 compresses better, but its encoder crashes this WebAssembly build of FFmpeg a frame or two in, a known limitation of running libvpx without thread support. This tool uses VP8, which is stable and much faster to encode. The result is a valid WebM that plays anywhere WebM plays; it is simply larger than a VP9 file would be.
If file size is what you care about most, h.264 in MP4 will beat VP8 comfortably. Choose WebM when the open format is the point.
Common questions
Is WebM better than MP4?
It is free of patent licensing, which is its main advantage. On file size, the VP8 encoding used here is not as efficient as h.264, so an MP4 will usually be smaller. MP4 also wins on universal playback, TVs, editors and older phones all take it without question.
Can I get VP9 instead?
Not in the browser. The VP9 encoder is not stable in this WebAssembly build, so offering it would just mean failed jobs. Reading VP9 files works fine, so converting the other way is not a problem.
Why is this slower than converting to MP4?
libvpx is slower than x264 in WebAssembly. Lower the resolution first if the file is long.