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Password Breach Checker

Check if your password has appeared in known data breaches. 100% private.

Your password is never sent to any server

Only the first 5 characters of the SHA-1 hash are sent, making it impossible to reverse-engineer your password. This uses the k-Anonymity model from Have I Been Pwned.

Enter Your Password

Security Best Practices

  • Use a unique password for every account. Password reuse is the top cause of account takeovers.
  • Store passwords in a password manager. You only need to remember one strong master password.
  • Enable two-factor authentication (2FA) on all important accounts for an extra layer of protection.
  • Aim for 16+ characters with a mix of uppercase, lowercase, numbers, and symbols.
  • Avoid dictionary words, names, dates, or common substitutions like "p@ssw0rd" in your passwords.

Breach data provided by Have I Been Pwned

Why Passwords Get Breached

Data breaches happen when attackers gain unauthorized access to a company's database of user credentials. Even companies with strong security get breached. When they do, the stolen passwords are compiled into lists that are shared and sold across the internet. Attackers use these lists in credential stuffing attacks, automatically trying leaked passwords across thousands of other websites.

The biggest risk is password reuse. If you used the same password on a small forum that got breached and on your primary email account, an attacker can use the leaked password to access your email, and from there, reset passwords on your banking, social media, and other critical accounts. Checking whether your passwords appear in known breach databases is a critical first step in protecting your accounts.

How k-Anonymity Keeps Your Password Private

This tool uses the k-Anonymity model developed by Troy Hunt for the Have I Been Pwned Pwned Passwords API. Instead of sending your full password or its complete hash to a server, the process works differently. First, your password is hashed with SHA-1 entirely in your browser using the Web Crypto API. Then, only the first 5 characters of that hash are sent to the API.

The API returns all hash suffixes that match those 5 characters, typically around 500 results. Your browser then checks whether the remaining characters of your password's hash appear in that list. This means the server never sees your password, never sees the full hash, and cannot determine which of the returned hashes you were checking. The privacy model ensures that even the API operator cannot figure out your password.

Password Best Practices for 2025 and Beyond

Modern password security goes beyond just choosing a long password. The most important practice is using a unique password for every single account. A password manager makes this practical by generating and storing strong passwords automatically. You only need to remember your master password.

Length matters more than complexity. A 20-character passphrase made of random words is harder to crack than a short 8-character password full of symbols. However, the ideal approach is combining both: use 16 or more characters with a mix of uppercase, lowercase, numbers, and special characters. Always enable two-factor authentication where available. Even if your password is compromised, a second factor prevents unauthorized access.

What to Do If Your Password Has Been Breached

If this tool shows that your password has appeared in a breach, take action immediately. Change that password on every account where you used it. Start with your most critical accounts: email, banking, cloud storage, and social media. Use your password manager to generate a unique replacement for each one.

After changing passwords, enable two-factor authentication on all accounts that support it. Check your accounts for any unauthorized activity, unfamiliar logins, changed settings, or suspicious transactions. Consider signing up for breach notification services so you are alerted when your email address appears in future breaches. Going forward, never reuse a password across multiple sites.

Frequently Asked Questions

Is it safe to type my password into this tool?

Yes. Your password never leaves your browser. The tool hashes your password locally using the Web Crypto API built into your browser, then sends only the first 5 characters of the SHA-1 hash to the Have I Been Pwned API. This k-Anonymity approach makes it mathematically impossible for anyone, including the API, to determine your actual password. You can verify this by checking the Network tab in your browser's developer tools.

How does the Have I Been Pwned API work?

The Pwned Passwords API uses a k-Anonymity model. When you check a password, your browser hashes it with SHA-1 and sends just the first 5 hex characters to the API. The API returns all known breach hashes that start with those 5 characters (typically around 500 results). Your browser then compares the rest of the hash locally. The server never receives enough information to identify your password.

My password was found in breaches. What should I do?

Change that password immediately on every account where you have used it. Use a password manager to generate unique, strong passwords for each account. Enable two-factor authentication where available. Check your accounts for unauthorized activity. If you used the breached password on your email account, prioritize changing that first since email accounts are often used to reset other passwords.

Does 'not found' mean my password is safe?

Not finding your password in the breach database means it has not appeared in any publicly known data breaches that Have I Been Pwned has collected. However, it does not guarantee the password has never been compromised in a private or unreported breach. Always follow password best practices regardless of the result: use unique passwords, enable two-factor authentication, and keep passwords long and random.

How many breached passwords does this check against?

The Have I Been Pwned Pwned Passwords database contains over 900 million unique passwords collected from verified data breaches around the world. The database is regularly updated as new breaches are discovered and processed. This makes it one of the most comprehensive sources for checking whether a password has been exposed.

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