Why compress a video?
Video files are big, and they hit limits fast: an email attachment that bounces, a messaging app that won't send, an upload form with a size cap, or a phone that's simply out of storage. Compressing a video re-encodes it more efficiently and, if you like, at a smaller resolution — cutting the file size dramatically while keeping it perfectly watchable.
The usual triggers are sending a clip to someone, uploading somewhere with a hard limit, or freeing up space. A screen recording, a phone video, or a short demo can often shrink by half or more with no difference you'd notice on a normal screen.
How it works
The compressor re-encodes your video to H.264 (MP4) — the most widely compatible format — at a lower bitrate, and can scale the resolution down depending on the level you choose. It does this using a WebAssembly build of FFmpeg running inside the page. Because that all happens on your own device with no server, there's no upload, no queue, and no watermark, and the output plays everywhere (it's written with faststart so it streams immediately on the web).
One honest caveat: browser-based video encoding is CPU-heavy and single-threaded, so it's genuinely best for short clips (up to a minute or two). A long video will work but can be slow on anything but a fast machine. The engine (~25–30 MB) downloads the first time you compress a video, then is cached for the rest of your session.
Choosing a level
Low keeps close to the original quality and resolution — a modest but useful reduction, good when the video will be watched full-screen. Medium is the sensible default: it caps resolution around 720p and re-encodes at a lower bitrate, which clears most email and upload limits without an obvious quality drop. High caps around 480p for the smallest possible file, ideal when size is the only thing that matters. If you need to hit a specific limit, start at Medium, check the result, and step up to High only if needed.
No upload, no watermark, no server
The clips most worth shrinking are often the private ones — family footage, a recording of internal work, something not yet public. Plenty of online compressors take your file up to their servers, stamp a watermark on it, and cap the size; this one does none of that, because the entire re-encode runs in your browser on your own machine. Want proof it never leaves your device? The how-we-prove-it page shows you, and you can always convert with the network off to see for yourself.
Frequently asked questions
Is my video uploaded to a server?
No. The compression runs entirely in your browser using a WebAssembly build of FFmpeg. The file never leaves your device.
Why is it slow / why does the first one take a while?
Browser video encoding is CPU-heavy and single-threaded, and the ~25–30 MB engine downloads on the first video. Short clips work best; after the first run the engine is cached.
What formats can I compress?
MP4, MOV, WEBM, AVI, MKV and M4V go in; the output is always a widely-compatible MP4 (H.264 + AAC).
Is there a watermark or size limit?
No watermark, and no server-imposed size limit — but very large files are limited by your own device's memory and speed.