Passphrase Lab

Privacy

What you send us

Your password stays on your device. To check it against known breaches, the page sends the first 5 characters of its SHA-1 hash to our server. Those 5 characters are shared by a large number of other passwords and are not enough to work out yours. How this works

What we do with it

Our server passes those 5 characters to the Pwned Passwords service of Have I Been Pwned and returns the answer. Our code writes no log and stores nothing. Our server makes that request, not your browser.

What we keep

Nothing from the checks. No account, no form, no cookies, no analytics script and no advertising. We save nothing on your device. This site loads nothing from other websites. Links to other sites open only when you tap them, and their own privacy policies apply there.

Who else is involved

Cloudflare hosts this site and runs our server code, so it handles your IP address and those 5 characters, under its own privacy policy. It may also ask your browser to report network errors to it. We read Cloudflare's traffic records, which include IP addresses, to count visits and remove bots. We do not use them to identify anyone.

Changes

If this changes, this page will say so first. If we add affiliate links, you will be asked at the first click, before any tracking.

Last updated: 30 October 2026.