How to use
- Drop a video file (MP4, WebM, MOV and more) into the box or click to select one from your device.
- Pick a compression level — Low keeps the most quality, Medium balances size and quality, High shrinks the file the most.
- Click Compress and let the in-browser engine re-encode your video with H.264; the first run downloads a ~30 MB engine, then it runs offline.
- Download the smaller, compressed MP4 once the progress reaches 100%.
Frequently asked questions
Is my video uploaded to a server?
No. The entire compression happens locally in your browser using ffmpeg.wasm. Your video file never leaves your device and is never uploaded to any server, so it stays 100% private.
Which video formats can I compress?
You can load MP4, WebM, MOV and most common video formats. Whatever you start with, the compressed result is always saved as an MP4 file with H.264 video and AAC audio for broad compatibility.
How much will the compression reduce my file size?
It depends on the level you pick and the source video. Low, Medium and High map to increasingly aggressive re-encoding (H.264 CRF 23, 28 and 32), so higher levels produce a noticeably smaller file at the cost of some visual quality.
Is there a file size limit?
There is no fixed upload limit because nothing is uploaded. The practical limit is your device's memory, since the whole video is processed in the browser. Very large or long videos take more time and RAM, so smaller clips compress fastest.
Why is the first compression slow?
On the first run the tool downloads a roughly 30 MB compression engine (ffmpeg.wasm). After that it is cached and runs offline, and processing speed mostly depends on your video's length, resolution and your computer's power.
Will compressing reduce the video quality?
Compression re-encodes the video, so some quality is traded for a smaller size — that is how the file shrinks. Choose Low for the best-looking result, or High when getting the smallest possible file matters more than fine detail.
About this tool
Compress video online to shrink MP4 and other files, free and 100% in your browser. Pick a Low, Medium or High level, re-encode with H.264, nothing uploaded.