Password Strength & Entropy Checker

What is Password Strength & Entropy Checker?

The Password Strength Checker evaluates password complexity, character diversity, theoretical Shannon entropy in bits, and estimated brute-force cracking times across multiple attacker hardware profiles. It checks for common dictionary words, repeated character sequences, and predictable keyboard patterns entirely in your local browser memory with zero network transmissions.

Designed for accuracy, speed, and privacy, this tool runs entirely on your local device with zero network latency.

How to Use the Password Strength & Entropy Checker

1. 1
   Type or paste your password into the secure input field above (click the eye icon to toggle character visibility).
2. 2
   Review the real-time strength meter (Very Weak, Weak, Fair, Strong, or Very Strong) and calculated Shannon entropy in bits.
3. 3
   Inspect the estimated time required to crack your password across online throttled services, offline fast GPUs, and supercomputer clusters.
4. 4
   Check the vulnerability checklist for recommendations on adding uppercase letters, lowercase letters, numbers, or special symbols.

Formula & Calculation Logic

Computes information entropy based on character set pool size N (lowercase=26, uppercase=26, digits=10, symbols=33, full pool=95) and password length L, adjusted downward for dictionary substrings and sequential patterns in accordance with NIST SP 800-63B.