Video compressor
Shrink videos for sharing — H.264 / MP4 with one-click presets. Runs locally in your browser.
Choose a video, or browse
MP4, MOV, MKV, WebM — up to 500 MB
Frequently asked
Does my video upload anywhere?+
No. Compression runs in your browser using ffmpeg.wasm. The file is never sent to any server.
What does CRF mean?+
CRF (Constant Rate Factor) is how H.264 measures quality. Lower = better quality and bigger files. 18 is visually lossless; 23 is the H.264 default; 28-30 is small but still watchable. Our presets pick sensible CRF values for you.
How much smaller will my file get?+
Depends entirely on the source. A modern phone recording is already H.264 — Balanced preset typically cuts it 40-60%. A high-bitrate screen recording or older DSLR file can shrink 80%+.
Why is it slow?+
H.264 encoding is genuinely CPU-heavy. ffmpeg.wasm uses multithreading where supported, but expect rough parity with native ffmpeg's veryfast preset — roughly real-time on a modern laptop, slower on phones.
Why MP4 only?+
MP4 with H.264 + AAC plays everywhere — iOS, Android, browsers, video editors, social media. Outputting WebM or other formats is possible but loses universal compatibility. We're optimising for 'just works'.