Video Compressor
Shrink a video's file size by re-encoding it at a lower bitrate, right in your browser.
About this tool
Shrinks a video's file size by re-encoding it (H.264 video, AAC audio) at a lower bitrate — real compression, not just a container change. Runs entirely in your browser using ffmpeg.wasm, a WebAssembly build of the real ffmpeg; your video is never uploaded anywhere.
The ffmpeg engine (about 32MB) is only downloaded the first time you use this tool, not when the page loads. Unlike trimming (which can skip re-encoding), compression always re-encodes the whole video, which takes real processing time — often longer than the video's own length, since this runs single-threaded WebAssembly with no hardware acceleration.
Frequently asked questions
- Why is this so much slower than my browser's own video player?
- Compression requires fully re-encoding the video frame by frame — there's no shortcut. This runs in WebAssembly without GPU hardware acceleration, so it's meaningfully slower than a native video editor. Expect processing time to be a multiple of the video's own length for anything but very short clips.
- What does "Compression level" actually change?
- It sets ffmpeg's CRF (Constant Rate Factor) — a lower value means higher quality and a larger file, a higher value means more compression and more visible quality loss. "Balanced" is a reasonable default for most videos.
- What format is the output?
- Always MP4 (H.264 video, AAC audio), regardless of your input format.
- Is my video uploaded anywhere?
- No — the entire process, including the ffmpeg engine itself, runs locally in your browser via WebAssembly. Nothing is sent to any server.