Video Compressor & Converter

The tool uses FFmpeg compiled to WebAssembly, running entirely in your browser. When you upload a video and click compress, the tool writes the file to a virtual filesystem inside the WASM runtime, runs the FFmpeg command with your chosen settings, and reads back the compressed output. No data is sent to any server — everything happens locally on your device.

The FFmpeg WebAssembly binary contains the full FFmpeg executable compiled to run in the browser. This ~30MB download happens once (and is cached by your browser for subsequent visits). After the initial load, you can compress videos with the same codecs and options as a desktop FFmpeg installation — H.264, H.265/HEVC, VP9, AAC, and more.

There is no hard limit, but very large or long videos will take longer to process and consume more browser memory. Videos under 500MB and under 10 minutes typically process within 1–5 minutes depending on settings and your device's CPU. For best results, start with shorter clips and use the trim feature to select only the portion you need.

CRF (Constant Rate Factor) controls quality — lower numbers mean better quality but larger files. The scale is 0–51: 0 is lossless (very large), 18 is visually lossless, 23 is the default (good balance), 28 is acceptable for web sharing, 32+ is heavily compressed. A CRF of 23 is recommended for YouTube uploads, 28 for Discord/Twitter, and 18 for archival quality.

Yes. You can convert between MP4, WebM, MOV, and MKV container formats with corresponding codec support: H.264 (MP4, MOV, MKV), H.265/HEVC (MP4, MKV), and VP9 (WebM). The tool automatically filters compatible codecs based on your selected output format.

The tool uses CRF-based encoding which preserves as much quality as possible for a given file size target. For near-lossless quality, use the 'High Quality' preset (CRF 18) or set CRF to values between 14 and 18. Keep in mind that transcoding always introduces some generational quality loss — for best results, encode from your original source file rather than a previously compressed video.

Yes, the tool is fully responsive and works on mobile browsers. However, video encoding is CPU-intensive and may take longer on mobile devices. The FFmpeg WASM engine works on all modern browsers (Chrome, Firefox, Safari, Edge) that support WebAssembly.

Each preset is tuned for a specific platform's recommended upload settings. YouTube works best with H.264, CRF 23, 1080p at 30 FPS. Twitter/X and Discord benefit from 720p with higher compression. Instagram supports 1080p. For maximum platform compatibility, the H.264 codec with AAC audio is recommended. Use the 'Small File' preset for sharing via messaging apps where file size limits apply.