Convert MP4 to WebM

Convert MP4 video files to WebM in your browser. VP9 + Opus codec — no upload, no watermark, no signup.

Drop an MP4 file here

or click to select a file

MP4 only — up to 2 GB

The FFmpeg engine (~25 MB) downloads on first use and is cached by your browser. Encodes with VP9 + Opus for modern web compatibility.

How to use

  1. Drop an MP4 file or click to select it from your device.
  2. Preview the video and click "Convert to WebM".
  3. Download the converted WebM file with VP9 + Opus encoding.

Frequently asked questions

Why use VP9 instead of VP8 for WebM?

VP9 delivers roughly 50% better compression than VP8 at the same quality. It is the current standard codec for WebM, supported by all major browsers since 2015. The WebM container technically allows VP8, but VP9 is the right choice for new files — smaller size with better quality.

Will the WebM file be smaller than the original MP4?

Often yes — VP9 is highly efficient, especially for screen recordings and animated content. For some already-compressed MP4s, the WebM may be similar in size. This tool uses a 1 Mbps target bitrate with realtime encoding speed for a good balance between speed and file size.

What is the maximum file size?

Up to 2 GB on desktop. Mobile browsers may struggle above 500 MB because the entire file must fit in browser memory. Nothing is uploaded to a server — your video stays on your device the whole time.

Is this tool free and does it add a watermark?

Completely free, no signup, no watermark, no time limit. The FFmpeg WASM engine runs locally in your browser — no video data ever leaves your device.

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