How to Use the Password Tester
Check whether your password has appeared in any known data breaches — without ever sending your actual password over the internet.
Step 1: Enter the password you want to check. Use the eye icon to toggle visibility.
Step 2: Click "Check Breach Database." The tool uses the k-Anonymity model: only the first 5 characters of a SHA-1 hash are sent to the API. Your full password never leaves your browser.
Step 3: Review the results. If the password appears in breach databases, you will see how many times it has been exposed.
Password Security in 2026: Why It Still Matters
Despite the rise of passkeys and biometric authentication, passwords remain the primary authentication method for billions of accounts worldwide. The average person has over 100 online accounts, and password reuse remains alarmingly common. When one service is breached, attackers use the leaked credentials to break into other accounts — a technique called credential stuffing.
How the k-Anonymity Check Works
The Have I Been Pwned database contains over 14 billion compromised accounts. Rather than sending your password to their servers, this tool uses a clever mathematical trick. Your password is hashed with SHA-1, and only the first 5 characters of the hash are sent to the API. The API returns a list of hash suffixes that match that prefix. Your browser then checks locally whether your full hash appears in the list. At no point is your password or its complete hash transmitted.
What To Do If Your Password Is Compromised
Change it immediately on every service where you have used it. Enable two-factor authentication wherever possible. Use a password manager to generate and store unique passwords for each account. Consider transitioning to passkey-based authentication where supported.
The Human Factor
The most common passwords in 2026 are still variations of "123456," "password," and "qwerty." No amount of technical security can protect an account with a weak password. The goal of tools like this is to make the abstract threat of "data breaches" tangible and personal — when you see that your specific password has been leaked thousands of times, the urgency becomes real.
Frequently Asked Questions
Yes. The tool uses the k-Anonymity API, meaning only a 5-character prefix of your password's hash is sent to the server. Your actual password never leaves your browser. You can verify this by reading the source code.
The count represents how many times that exact password has appeared in data breaches compiled by Have I Been Pwned. A count of 50,000 means it has been exposed in at least 50,000 records across various breaches.
It means your password has not appeared in any of the known breaches in the database. However, it does not guarantee the password is strong. Always use long, unique passwords with a mix of character types.