Compress video
Smaller files for sharing — CRF knob, in your browser.
Drop a video, or click to choose
MP4, WebM, MOV, MKV. Runs entirely in your browser. Larger files take longer.
About Compress video
Shrink large MP4 and MOV videos so they're easy to share over email or messaging. Pick a quality level (CRF), and the tool re-encodes the video in your browser using ffmpeg.wasm. Nothing is uploaded — your video stays local the whole time.
Frequently asked questions
How much smaller will my video be?+
Typically 50-80% smaller, depending on the quality setting.
Does it run in my browser?+
Yes — ffmpeg.wasm runs locally. The file never leaves your device.
What formats are supported?+
MP4, MOV, WebM, and MKV input. Output is MP4 (H.264).
Why is it slower than a desktop app?+
Browser-based ffmpeg is roughly 3-5× slower than native ffmpeg. For very long videos, a desktop tool is faster.
What's the CRF value?+
Constant Rate Factor — lower number means higher quality and larger file. The default of 23 is a good balance.