Password Strength Checker: Test Your Security Instantly

Are you wondering if your password is truly protected against brute-force attacks? Our password strength checker instantly analyzes the complexity of your credentials using precise entropy calculations and data breach detection. Completely free and 100% client-side, this tool ensures that your sensitive information never leaves your device, providing maximum security without any data storage. Test the strength of your passwords now with professional-grade technical accuracy.

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How to evaluate password strength?

A password strength checker analyzes multiple dimensions: length, character diversity, absence of predictable patterns and entropy (measured in bits). Our tool uses fully client-side analysis — your password never leaves your browser.

What is HIBP verification?

HaveIBeenPwned (HIBP) is a database of over 10 billion passwords compromised in data breaches. Our tool uses the k-anonymity method: only the first 5 characters of your password's SHA-1 hash are sent to the API — your full password is never transmitted.

Why avoid predictable patterns?

Dictionary and rule-based attacks exploit common substitutions (a→@, e→3), keyboard sequences (qwerty, azerty), dates, and common passwords. A password like "P@ssw0rd!" meets complexity criteria but is extremely vulnerable as it appears in every common password list.

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