Password Leak Checker

Yes, this is completely safe. Your password is hashed locally in your browser using SHA-1 before any network request is made. Only the first 5 characters of the 40-character hash are sent to the HIBP API. This makes it mathematically impossible to determine your actual password from the transmitted data. The full hash (and therefore your password) never leaves your device. This k-Anonymity approach is the same method used by 1Password, Firefox, and other security-focused organizations when checking for breached passwords.

Have I Been Pwned (HIBP) is a free online service created in 2013 by Troy Hunt, a respected security researcher and Microsoft Regional Director. It aggregates data from publicly disclosed data breaches and allows individuals to check if their personal information has been compromised. The service indexes over 12 billion breached accounts and 850 million unique passwords. HIBP is trusted by governments, major corporations, password managers, and web browsers. The service is designed with privacy as a core principle, implementing k-Anonymity for password checking.

The breach count shows how many times this exact password has appeared across all known data breaches in the HIBP database. A higher number indicates the password is more commonly used and therefore more likely to be targeted by attackers. For example, if a password appears 1,000,000 times, it's probably a common password like "password123" that's in every attacker's dictionary. Even appearing once means the password has been exposed and should be changed immediately - attackers actively use breach data for credential stuffing attacks.

Not necessarily. A password not being found in known breaches is good news, but it doesn't guarantee security. The HIBP database only contains passwords from publicly disclosed breaches - many breaches are never reported or are sold privately on dark web forums. Additionally, a password could be weak or easily guessable even if it hasn't been leaked yet. Best practice is to use strong, unique passwords (16+ characters with mixed types) for each account, even if they haven't appeared in known breaches. Continue using a password manager and enable 2FA for comprehensive protection.

Troy Hunt updates the Have I Been Pwned database regularly as new breaches are disclosed and verified. Major breaches are typically added within days of public disclosure. The password database is periodically updated with newly discovered password sets. However, there's always a lag between when a breach occurs and when it becomes publicly known - some breaches aren't discovered for months or years. This is why it's important to use unique passwords for every account, so a single breach doesn't compromise multiple services.

Yes, regularly checking your passwords is an excellent security practice. Start with your most critical accounts: email (which can reset other passwords), banking, social media, and cloud storage. If you use a password manager like 1Password or Bitwarden, they often have built-in breach checking that automatically monitors all your stored passwords. For accounts you're still manually tracking, check passwords at least every 6 months or whenever you hear about a major breach affecting services you use. Any password found in breaches should be changed immediately and never reused.