Password Leak Checker

🔑 Enter Password to Check

🔒 Your password is never sent to any server - only a partial hash is used

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📖 Complete Guide to Password Breach Checking

Data breaches are an unfortunate reality of the digital age. Every year, billions of passwords are exposed through hacks, leaks, and security failures at companies of all sizes. Our Password Leak Checker allows you to safely verify whether your passwords have appeared in any known data breaches, using the secure Have I Been Pwned (HIBP) API with a privacy-preserving technique called k-Anonymity.

Using a compromised password puts all your accounts at risk. Attackers regularly use "credential stuffing" - automated attacks that try leaked username/password combinations against thousands of websites. If you've reused a password that appeared in a breach, hackers may already have access to your accounts.

🔒 How k-Anonymity Keeps Your Password Private

The genius of k-Anonymity is that it allows us to check if your password has been breached without ever revealing your actual password to any external service. Here's exactly how the process works:

Step	Action	Privacy Protection
1. Local Hash	Your password is hashed using SHA-1 in your browser	Password converted to 40-character hash locally
2. Prefix Extraction	Only the first 5 characters of the hash are extracted	35 characters remain secret on your device
3. API Request	5-character prefix sent to HIBP API	API cannot determine your actual password from prefix
4. Receive Matches	API returns ~500 hash suffixes starting with that prefix	Your specific hash hidden among hundreds of others
5. Local Comparison	Your browser checks if your full hash is in the list	Full hash never leaves your device

📊 Understanding Breach Counts

When a password is found in breaches, we display how many times it has appeared. Here's what different counts typically indicate:

Breach Count	Risk Level	Recommended Action
1-100	⚠️ High Risk	Change immediately on all accounts
100-10,000	🔴 Very High Risk	Change immediately; password is commonly used
10,000-1,000,000	🔴 Extreme Risk	This is a very common password; change and never reuse
1,000,000+	💀 Critical	One of the most common passwords (like "123456"); immediate action required
0 (Not Found)	✅ Good (but verify)	Not in known breaches, but ensure it's still strong

🌐 What is Have I Been Pwned?

Have I Been Pwned (HIBP) is a free service created by Troy Hunt, a renowned security researcher and Microsoft Regional Director. The service aggregates data from publicly disclosed data breaches and allows people to check if their personal information has been compromised. Key facts about HIBP:

Database Size: Over 12 billion compromised accounts indexed
Password Database: Over 850 million unique passwords from breaches
Trusted By: Governments, banks, 1Password, Firefox, and major corporations
Privacy Focus: Implements k-Anonymity to protect user queries
Free to Use: No cost for personal use and basic API access
Open Source: The k-Anonymity API design is publicly documented

🛡️ Privacy Guarantee: The HIBP API never receives your actual password or even your complete hash. Only a 5-character prefix (out of 40 total characters) is transmitted. This means there are over 16 million possible passwords that could match any given prefix - making it mathematically impossible for HIBP to determine which password you're checking. This privacy-preserving method is used by 1Password, Firefox, and other major security-focused organizations.

📈 Major Data Breaches to Be Aware Of

Breach	Year	Records Exposed	Data Types
Collection #1-5	2019	2.2 billion	Emails, passwords from multiple breaches
LinkedIn	2012/2021	700 million	Emails, passwords, profile data
Facebook	2019	533 million	Phone numbers, names, emails
Adobe	2013	153 million	Emails, encrypted passwords
MySpace	2016	360 million	Emails, passwords, usernames

🎯 What To Do If Your Password Was Compromised

Immediate Steps:

Change the password immediately on any account where you've used it

Check all accounts using that email/username for unauthorized activity

Enable 2FA/MFA (two-factor/multi-factor authentication) on all important accounts

Review connected apps and revoke access to anything suspicious

Check financial accounts for unauthorized transactions

Long-Term Security Improvements:

Use a password manager to generate and store unique passwords for every account

Create unique passwords for each account - never reuse passwords

Use 16+ character passwords with mixed character types

Set up breach alerts at haveibeenpwned.com for your email addresses

Regularly check passwords - perform a security audit every 6 months

Consider hardware security keys for critical accounts (Google, banking)

If Your Password Was NOT Found:

Good news! But remember this only checks known public breaches

Private/unreported breaches may still contain your password

Still ensure password strength - "not breached" doesn't mean "secure"

Continue good practices - unique passwords, 2FA, password manager

Check regularly - new breaches are discovered constantly

❓ Frequently Asked Questions

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.

📖 Complete Guide to Password Breach Checking

🔒 How k-Anonymity Keeps Your Password Private

📊 Understanding Breach Counts

🌐 What is Have I Been Pwned?

📈 Major Data Breaches to Be Aware Of

🎯 What To Do If Your Password Was Compromised

Immediate Steps:

Long-Term Security Improvements:

If Your Password Was NOT Found:

❓ Frequently Asked Questions

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Password Leak Checker

📖 Complete Guide to Password Breach Checking

🔒 How k-Anonymity Keeps Your Password Private

📊 Understanding Breach Counts

🌐 What is Have I Been Pwned?

📈 Major Data Breaches to Be Aware Of

🎯 What To Do If Your Password Was Compromised

Immediate Steps:

Long-Term Security Improvements:

If Your Password Was NOT Found:

❓ Frequently Asked Questions

Why Ads?

Found a Bug?

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