KeythenticHome / Free tools / Breach check
Has this password been breached?
Check a password against hundreds of millions of leaked passwords without revealing it, to us or anyone else.
Sends 5 hash characters, only when you click CheckWhat will be sent
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The highlighted 5 characters of the SHA‑1 hash are all that leaves this page. The crossed-out part and your password stay here.
How it stays private
1. Your browser hashes the password with SHA-1On this page
2. The first 5 characters are sent to Pwned PasswordsSent
3. It replies with every hash starting with them, plus random padding~2,000 hashes
4. Your browser looks for your full hash in that listOn this page
The service only sees a prefix shared by about two thousand passwords, so it can’t tell which one you checked or whether it matched. This is the same method Keythentic uses in the app.