A professional password strength checker built in Python using the powerful zxcvbn library.
This tool evaluates password security using real-world attack simulations instead of simple rule-based checks.
. Real-world password strength estimation
. Detects common passwords
. Detects dictionary words
. Identifies keyboard patterns (e.g., qwerty, 12345)
. Detects repeated characters and sequences
. Handles leetspeak substitutions (e.g., p@ssw0rd)
. Provides crack time estimates
. Gives actionable improvement feedback
. Score rating from 0 (Very Weak) to 4 (Very Strong)
This project uses the zxcvbn library, originally developed by Dropbox.
Unlike basic password checkers that only validate: . Length . Uppercase letters . Numbers . Special characters
zxcvbn analyzes password patterns and estimates how long it would take for an attacker to crack the password using:
. Online throttled attacks . Online unthrottled attacks . Offline slow hashing attacks . Offline fast hashing attacks
It returns: . Strength score (0–4) . Estimated crack time . Security warnings . Improvement suggestions