The security corner

SHA-256 fingerprint of a file

Drop any file in and its fingerprint appears. Paste the one the download site publishes, and the tool tells you whether the two match, character by character.

Any type of file500 MB per file

Drop a file hereAny type of file. Nothing will be sent: the bytes are read here, on your device.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

This tool does not look at the contents of your file: it reads its bytes and hashes them. There is therefore no list of formats, and nothing that can go wrong because of one.

VerifyThe proof, step by step

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

The cornerThe security 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.