Compress Video Online - MP4 & WebM Compressor
Reduce video file size using FFmpeg. Compress MP4 and WebM with adjustable quality, resolution, and speed presets.
Runs in your browser. No data leaves your device.
Frequently Asked Questions
How does the Video Compressor work?
The tool loads FFmpeg.wasm, a WebAssembly port of FFmpeg, which runs entirely in your browser. Your video file is mounted via WORKERFS so FFmpeg reads it lazily from disk without copying it into RAM. FFmpeg then re-encodes the video using H.264 (for MP4) or VP9 (for WebM) with your chosen CRF quality, encoding speed preset, and resolution scale. The compressed output is served as a downloadable blob.
What video formats are supported?
You can compress to MP4 (H.264) or WebM (VP9). Most common input formats work including MP4, MOV, AVI, MKV, and WebM. The output is a compressed file in your chosen format and quality settings.
Why is browser compression slower than desktop apps?
FFmpeg runs in a single-threaded WebAssembly environment in the browser, which is slower than native apps. For large files, expect several minutes. Choosing the Ultrafast preset and reducing resolution will speed things up.
How much smaller will my video be?
Results vary by content, quality setting, and resolution. Typical reductions range from 30 to 80 percent. Lowering the quality slider, reducing resolution, and removing audio all reduce file size further.