Compress Video Without Uploading
Shrink large videos without sending them anywhere. The encoding engine runs in your browser tab — after a one-time download, even gigabyte-sized files stay on your device.
How it works
- Open this page — the first visit downloads a one-time ~9 MB encoding engine with visible progress.
- Drop in an MP4, MOV or WebM file; it is read straight from your device, never uploaded.
- Pick a quality level and a resolution cap (720p saves the most time and space).
- Watch the live progress bar, then download the compressed MP4.
When this helps
- Fitting a phone video under an email or chat attachment limit.
- Compressing family footage that should never sit on a third-party server.
- Shrinking screen recordings before attaching them to tickets or docs.
- Working on a slow or metered connection where uploading gigabytes is impractical.
Limits and notes
- Encoding is single-threaded: roughly real-time for 720p on a desktop, slower on phones.
- Files above ~500 MB may hit browser memory limits — close other tabs first.
- The engine download is one-time and cached by the browser afterwards.
Why compress video locally
Server-based video compressors ask you to upload the whole file first — slow on any connection, and a non-starter for private footage. This page downloads a small engine once, then does H.264 encoding in your browser tab. Open your network panel: apart from that first download, nothing goes upstream.
What you can do next
FAQ
Is my video uploaded anywhere?
No. The encoding engine (a WebAssembly build of FFmpeg) runs in this tab and the video is read straight from your device. Open your network panel: apart from the one-time engine download, nothing goes upstream.
Why does the first compression take a moment to start?
The first visit downloads the encoding engine (about 9 MB compressed). It is cached by your browser afterwards, so later visits start immediately.
How much smaller will my video get?
It depends on the source, but the Balanced preset plus the 720p cap typically cuts phone footage by 50–80%. Already-compressed videos shrink less.
Why is it slower than a desktop app?
Encoding runs single-threaded in WebAssembly — roughly real-time speed for 720p on a desktop, slower on phones. Capping the resolution is the biggest time saver.