About Password Strength Checker

Evaluate password strength based on length, character variety, uniqueness, and sequential pattern detection. The scorer awards points for length (12+ and 16+ thresholds), lowercase, uppercase, digits, symbols, character diversity (60%+ unique), and absence of sequential runs like “1234” or “abcd.” Results display a 4-bar strength meter (Weak/Fair/Good/Strong), Shannon entropy in bits, a requirements checklist, and actionable suggestions for improvement. Everything runs client-side—passwords are never transmitted.

• Entropy calculation: log₂(charset size) × password length
• Charset detection: lowercase (26), uppercase (26), digits (10), symbols (33)
• Sequential pattern detection catches common runs like 1234, abcd, etc.
• Character uniqueness check requires 60%+ distinct characters relative to length
• Five-point requirements checklist with pass/fail indicators
• Toggle password visibility; copy to clipboard

Frequently Asked Questions

What entropy value indicates a strong password?

Above 60 bits is solid for most purposes. Above 80 bits is excellent. A 16-character password using all four character classes (lowercase, uppercase, digits, symbols) yields roughly 105 bits—well beyond brute-force feasibility.

Does this check against known breached passwords?

No. It evaluates structural complexity only—length, character diversity, and pattern avoidance. A password like “CorrectHorseBatteryStaple1!” would score well here but should still be checked against breach databases like Have I Been Pwned separately.