Online Video Compressor — Reduce MP4 File Size

About this tool

Compress MP4 videos online for free using local FFmpeg WebAssembly in your browser. Choose light, balanced or strong CRF compression and maximum output width to shrink file size with zero video uploads.

Why can a compressed video still be large?

Duration, resolution, scene complexity and the original codec all affect size. A higher CRF usually means fewer bytes and less detail; a smaller maximum width can suit a small-screen copy. Already efficient clips may shrink very little or even grow. Compare quality and size on the same excerpt before keeping the export.

Questions & answers

How do I use Compress video?

Choose a video, set CRF and maximum width, then export. Higher CRF usually means a smaller file and lower quality.

What limits should I know about?

Speed and compatibility depend on browser, codecs and memory. Prefer short inputs and save results before closing the page.

Where do my files and data go?

Your media is processed in this browser, not uploaded to this site. Save results before refreshing or closing.