Password Leak Checker
NewCheck whether a password has been exposed in a known data breach using the Have I Been Pwned (HIBP) k-anonymity model. The tool computes a SHA-1 hash of your password locally and shows only the first 5 characters of the hash — your actual password is never transmitted anywhere. You can then manually query the HIBP API with the hash prefix to see if your password appears in their breach database. This implements the secure Pwned Passwords k-anonymity approach.
Password Leak Checker
Check if your password has appeared in known data breaches using the k-Anonymity method (only the first 5 chars of the SHA-1 hash are used).
Your password is hashed locally with SHA-1. Only the first 5 characters of the hash are sent to HIBP API. Your actual password never leaves your device.
How to Use Password Leak Checker
- 1Enter the password to check (never transmitted)
- 2The SHA-1 hash is computed locally
- 3Use the first 5 chars of the hash to query HIBP API
- 4Check if your password appears in breaches
Your Privacy is Protected
Password Leak Checker runs entirely in your browser. Your files and data are never uploaded to any server, never stored, and never shared. Everything happens locally on your device using secure browser APIs.
Frequently Asked Questions
Is my password safe to enter here?
Yes. The password is hashed locally in your browser. Only the first 5 characters of the SHA-1 hash are shown — your password is never sent to any server.
What is k-anonymity?
K-anonymity means only the hash prefix (not your full password or hash) is needed to query the breach database, protecting your privacy completely.
Why Use This Tool?
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