Password Breach Checker
Check if your password has been exposed in a data breach. Your password never leaves your device — we use k-anonymity to keep it completely private.
Your password never leaves your device
We hash it locally, then send only 5 characters of that hash to HaveIBeenPwned using the k-anonymity model. The full password and hash are never transmitted.
Enter a password to check if it's been breached
Checked against 900 million+ real-world breach records
100% Private
Your password is hashed locally. Only 5 characters of the hash go to the API. The server never sees your password.
900M+ Passwords
The HaveIBeenPwned database holds over 900 million real passwords from hundreds of public data breaches.
K-Anonymity Model
Only the first 5 chars of a SHA-1 hash are sent. The API returns all matching suffixes and your device checks locally.
Instant Results
Checks happen in under a second. No account, no email, no tracking — just instant breach verification.
Frequently Asked Questions
Is my password sent to any server?
No. Your password never leaves your device. We hash it locally using the Web Crypto API, then send only the first 5 characters of that hash to the HaveIBeenPwned API — never the password or full hash.
What is the HaveIBeenPwned Pwned Passwords API?
HaveIBeenPwned is a database of over 900 million passwords exposed in real-world data breaches. The Pwned Passwords API uses k-anonymity so you can check passwords without ever exposing them.
What does 'pwned' mean?
A password is 'pwned' if it has appeared in at least one known data breach. Even if it was someone else's account, attackers now have that password in their dictionaries and will try it against yours.
How many times does a password need to appear before I should worry?
Even once is enough to change it. A password that appears even once in breached data is known to attackers and should be replaced immediately with a unique randomly generated password.
What is k-anonymity?
K-anonymity is a privacy technique where only a partial SHA-1 hash prefix (5 characters) is sent to the API. The server returns all matching hash suffixes, and your device checks locally — the server never knows which password you checked.
What should I do if my password is breached?
Change it immediately on every site where you used it. Use a password manager to generate a unique random password for each account. Enable two-factor authentication wherever available.
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