Free Password Strength Checker
Test your password strength instantly with our free, privacy-first tool. 100% browser-side - your password never leaves your device.
Test Your Password
Enter a password to analyze (we recommend using a test password, not your real one)
🔍 Verify Our Privacy Claims
Don't trust us? Verify yourself: Open your browser's Developer Tools (F12) → Go to Network tab → Test a password → You'll see zero network requests. All processing happens in your browser.
🛡️ Want to learn more about our security? Read our Privacy & Security Architecture page to understand how we protect your passwords using client-side processing and k-anonymity breach checks.
How It Works
Type Your Password
Enter the password you want to test (or a similar pattern)
Instant Analysis
See strength score, entropy, crack time, and detailed feedback
Follow Recommendations
Get specific suggestions to improve your password security
Optional: Quantum Analysis
Upgrade to $1 premium for quantum resistance estimates
What You Get
📊 Entropy Calculation
Measures the randomness and unpredictability of your password. Higher entropy = stronger password.
⏱️ Crack Time Estimates
See how long it would take to crack your password with modern hardware (GPUs).
🔍 Pattern Detection
Identifies common patterns, dictionary words, keyboard patterns, and repeated characters.
💡 Smart Suggestions
Get specific, actionable recommendations to improve your password strength.
⚛️ Quantum Resistance Preview
See if your password is future-proof against quantum computers (basic estimate).
🎯 Strength Score
Simple 0-4 score showing password strength at a glance (very weak to very strong).
Want to Check if Your Password Has Been Breached?
Our Password Breach Check feature uses the Have I Been Pwned database to check if your password has appeared in known data breaches.
🔒 How It Works (Privacy-First)
- k-Anonymity Model: Your password is hashed using SHA-1 in your browser
- Only 5 characters of the hash are sent to our API (99.9875% kept private)
- Zero-knowledge: Neither we nor Have I Been Pwned ever see your actual password
- Instant results: Find out if your password appears in 800+ million breached passwords
⚠️ Note: Breach checking requires an API key because it makes external requests to the Have I Been Pwned database. This feature is available with:
The free password strength checker above is 100% client-side and requires no API key.
Trusted by Security-Conscious Users
Join thousands of people who use our free tool to test and improve their password security
Frequently Asked Questions
Is it safe to test my real password here?
Technically yes, but we recommend testing a similar password instead. All analysis happens 100% in your browser - your password never leaves your device. However, as a best practice, test a password with a similar pattern rather than your actual password. This protects you from keyloggers, screen recording malware, or shoulder surfing.
How can I verify this is really client-side?
Easy! Here's how to verify:
- Open your browser's Developer Tools (press F12 or right-click → Inspect)
- Go to the "Network" tab
- Type a password in our checker
- Watch the Network tab - you'll see zero requests to our servers
This proves your password stays in your browser. You can also view our open-source code on GitHub.
What makes a password "strong"?
A strong password has these characteristics:
- Length: At least 12-16 characters (longer is better)
- Character diversity: Mix of uppercase, lowercase, numbers, symbols
- No patterns: Avoid "password123", "qwerty", birthdays, names
- High entropy: 60+ bits for classical security, 80+ for quantum resistance
- Uniqueness: Different password for each account
- Not breached: Check against known breach databases (available with our Premium or API access)
Can I check if my password has been in a data breach?
Yes! We offer a Password Breach Check feature that uses the Have I Been Pwned (HIBP) database to check if your password appears in over 800 million breached passwords from known data breaches.
How it protects your privacy: Your password is hashed using SHA-1 in your browser, and only the first 5 characters of the hash are sent to our API using k-anonymity. This means 99.9875% of your password hash remains completely private. Neither we nor HIBP ever see your actual password.
This feature requires an API key and is available with our Premium access ($1) or Developer API (free tier available).
Do I need to register or create an account?
No! Our free password checker requires no registration, no account, no email address - nothing. Just visit the page and start testing. It's free forever.
(You only need an account if you want to use our Developer API to integrate password checking into your own application.)
What's the difference between free and premium?
Free tool (this page):
- Password strength analysis
- Entropy calculation
- Crack time estimates
- Pattern detection
- Basic security recommendations
Premium ($1 one-time):
- Everything in free, PLUS:
- Detailed quantum resistance analysis (3 scenarios)
- Phonetic password generator (creates memorable, strong passwords)
- Educational quantum security guide
Want Quantum Resistance Analysis?
Upgrade to premium for detailed quantum computing resistance estimates and our phonetic password generator. One-time payment of just $1.
Try Premium Features - $1One-time payment • Lifetime access • Educational quantum analysis
Are You a Developer?
Integrate password strength checking into your application with our API. Free tier available with 25 requests per month.
View Developer API