The everyday corner

Zip and unzip an archive

The browser can compress, but it can neither work out a CRC-32 nor write a zip container: both of those are written by hand here, and the archive we produce is REOPENED by our own reader before it is handed to you.

Any type of file, or an archive200 MB per file

Drop in files to archive, or an archive to openSeveral files to build a zip, a single archive to open one.Choose a file

This file is beyond what this tool does

This tool needs JavaScript to work, and that is precisely because it works ON YOUR DEVICE: without JavaScript, your file would have to be sent to a server. The instructions and the limits of the tool, however, can be read without JavaScript, just below.

How this is built

Your file never leaves your device

This tool works entirely inside your browser. Not one byte of your file is sent anywhere, and nothing is kept once the tab is closed.

Checkable in ten seconds, without taking our word for it:

Open your browser's inspector: the F12 key (or Ctrl+Shift+I, or Cmd+Option+I on a Mac).
Go to the “Network” tab, then clear the list.
Process a file on this page. The list stays empty: no request goes out.
To go further: cut your connection and do it again. The tool still works.

This absence of requests is also checked BY MACHINE before every release: a lock drives a real browser, processes a real file, and refuses to publish if a single byte goes out.

The proof page, step by step and in pictures

Going further

InstructionsHow it works

Any files at all to build an archive; a single zip archive to open one. The mode is worked out from the FIRST FOUR BYTES of the file you drop in, not from its name.

VerifyThe proof, step by step

The network inspector check, explained one gesture at a time, with screenshots.

The cornerThe everyday corner

The other tools in this corner of the workshop.

UnderstandHow this is built

The formats actually handled, browser by browser, and what we ruled out.