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🔒 Password Strength Checker

Analyze password strength, entropy, crack time estimation and get security tips — 100% private, client-side only.

Enter Password
Enter a password
Checking against common passwords…
Entropy —
0 bits40 bits80 bits120+ bits
Analysis
0 Score
⚡ Estimated Crack Time
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Enter a password to see crack time
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Length
0
Uppercase
0
Lowercase
0
Digits
0
Symbols
0
Unique Chars
0
Char Pool
0
Entropy (bits)
Security Checklist
Scoring Breakdown
History
No passwords checked yet
Patterns to Avoid
❌ Sequential: 123456, abcdef
❌ Keyboard: qwerty, asdfgh
❌ Repeats: aaaaaa, 111111
❌ Common words: password, admin
❌ Leet speak: p@ssw0rd
❌ Dates: jan2024, 01/01/90
✅ Use passphrases: 4+ random words
✅ Mix case, digits, symbols
✅ 16+ characters ideal
Privacy
✅ 100% client-side — password never sent to any server
✅ Analysis runs entirely in your browser

Password Security Guide

What is Entropy?

Password entropy measures how unpredictable a password is in bits. It's calculated as log₂(pool_size^length). 40+ bits = weak, 60+ bits = fair, 80+ bits = strong, 100+ bits = very strong.

Crack Time Explained

Crack time estimates assume a modern GPU can attempt ~10 billion hashes/second for offline attacks. Online attacks are typically throttled to ~1000/second. Salted hashes (bcrypt, Argon2) are much more resistant.

Passphrases

Four random words (e.g., "correct horse battery staple") can have 44+ bits of entropy and are easier to remember than complex 8-character passwords. Length matters more than complexity.

Best Practices

Use a unique password for every account. Enable 2FA wherever possible. Use a password manager (Bitwarden, 1Password) to generate and store strong passwords. Never reuse passwords.