TR ToolRux

Data Breach Checker

Check if your passwords have appeared in known data breaches. Privacy-first with k-Anonymity — your password never leaves your browser.

Password Breach Check

Check if a password has appeared in known data breaches using the Have I Been Pwned API.

🔒 Privacy First

Your password is never sent over the network. It is hashed with SHA-1 locally in your browser. Only the first 5 characters of the hash are sent to the API (k-Anonymity model). The API returns all matching suffixes, and the comparison happens locally.

After a Breach — What to Do

Change your password immediately

Use a unique, strong password with 12+ characters. Mix uppercase, lowercase, numbers, and symbols.

Enable Two-Factor Authentication

Add an extra layer of security with TOTP or hardware keys wherever possible.

Use a password manager

Generate and store unique passwords for every account. Never reuse passwords.

Check your other accounts

If you used the same password elsewhere, change those passwords too.

Monitor for suspicious activity

Watch for unauthorized logins, password reset emails, or unusual account activity.

Related Articles

Learn more about this topic

Related Tools

You might also find these useful

Password Strength Checker

Test if your password is strong.

Password Generator

Generate a new strong password.

Encryption Tool

Encrypt sensitive data.
📖 Learn More

Everything you need to know

Why Check for Data Breaches

Over 12 billion accounts have been exposed in data breaches worldwide. If you reuse passwords or use common passwords, there's a high chance your credentials are in a breach database. Attackers use "credential stuffing" — automatically trying leaked email/password combinations across thousands of websites. Checking your passwords against known breaches is the first step in protecting your accounts.

How the Privacy Model Works

This tool uses the Have I Been Pwned Pwned Passwords API with a k-Anonymity privacy model. Your password is hashed with SHA-1 entirely in your browser. Only the first 5 characters of the 40-character hash are sent to the API. The API returns all hash suffixes matching that prefix (typically 500-800 entries). The comparison between returned suffixes and your full hash happens locally in your browser. The API never sees your password or its complete hash.

What to Do After a Breach

If your password appears in a breach: change it immediately on all accounts where it was used, enable two-factor authentication (2FA) wherever available, start using a password manager like 1Password, Bitwarden, or KeePass to generate unique passwords per account, and monitor your accounts for unauthorized activity or password reset emails you didn't request.

Building Strong Passwords

Use passwords with 12+ characters containing uppercase, lowercase, numbers, and symbols. Better yet, use random passphrases of 4-5 words. Never reuse passwords across sites. Let a password manager generate and remember strong, unique passwords for every account. Check your password strength with our Password Strength Checker.

Related Security Tools

Test your password strength with the Password Strength Checker, set up two-factor authentication with the TOTP Generator, or encrypt sensitive data with the Encryption Tool.