Are my files uploaded to a server?

No. Everything runs locally in your browser using JavaScript. Your files never leave your device and nothing is sent over the network.

Is there a file size or count limit?

There is no artificial limit. The practical limit is your device's available memory, since files are processed in-browser.

Do I need an account?

No. There is no sign-up, no account, and no tracking. The tool is free to use.

Zip & Unzip Files Online — Free, Private, In Your Browser

Bundle files into a .zip, or extract an existing archive — all in your browser.

How to zip files online (free)

Stay on the Create ZIP tab and drop your files onto the box above.
Review the list and remove anything you don't want.
Give the archive a name and click Create ZIP.

How to unzip / extract a ZIP file

Switch to the Extract ZIP tab and drop your .zip onto the box.
The files inside are listed instantly.
Download files individually, or use download all.

Why katlab's zip tool is different

Most "online zip" sites upload your files to their servers to process them. This one doesn't. Everything — compression, extraction, download — happens inside your browser tab using JavaScript. Your files never touch the network, so there's nothing to leak, cache, or delete later.

Is it really private?

Yes. There is no upload step and no account. You can open your browser's network tab and watch: no request carries your file data. The tool works offline once the page has loaded.

Is there a size limit?

There's no artificial cap. Because files are held in memory while processing, the real limit is your device's available RAM — comfortable for everyday documents, images, and code, and fine for most large archives too.

What formats can it open?

It reads standard .zip archives. Support for other formats like .tar.gz and .rar is on the roadmap as separate katlab tools.