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Local Password Breach Checker - Online k‑Anonymity

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Local Password Breach Checker

Check if your password has been exposed — safely with k‑anonymity

Your password never leaves your browser. Only a partial hash is sent to the API.

We never store or send your password. Learn more
Checking...

Contacting breach database (k‑anonymity safe)...

How k‑anonymity keeps you safe

Instead of sending your actual password, this tool:

  1. Hashes your password with SHA‑1 inside your browser.
  2. Sends only the first 5 characters of that hash to the Pwned Passwords API.
  3. The API returns a list of matching hash suffixes (the rest of the hash).
  4. We locally compare your full hash against the list — your password never leaves your device.

Why this tool?

No password transmission – full password stays local.
🔒 Trustless design – even we can’t see your password.
Instant results – powered by Have I Been Pwned API.
📱 Fully responsive – works on all devices.

Frequently Asked Questions

k‑anonymity ensures that even the service performing the check cannot determine your password. Only a small part of the hash (the prefix) is shared, making it impossible to reverse‑engineer the original password from the request.

No. The password is never sent to our server and is used only for the immediate SHA‑1 calculation inside your browser. We do not log or store anything.

Using a breached password puts all your accounts at risk from credential stuffing attacks. Checking helps you avoid reusing compromised passwords and encourages good password hygiene.

Immediately change that password on all services where you use it. Consider using a password manager to generate strong, unique passwords for every account.

We query the public Pwned Passwords service by Troy Hunt, which contains hundreds of millions of real‑world leaked passwords.