HTMLPassword Strength Checker
Analyze any password's strength with a detailed breakdown: entropy (bits), character set size, length score, presence of uppercase, lowercase, digits, symbols, and detection of common patterns (dictionary words, keyboard walks, repeated characters, sequences). Rates overall strength as Weak, Fair, Good, or Strong.
Ctrl+Enter to run | Ctrl+K to switch tools | Recent button shows input history
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Does this send my password anywhere?
No — all analysis runs in your browser using JavaScript. Nothing is transmitted or logged.
What is entropy?
Entropy (measured in bits) is a mathematical measure of unpredictability. Higher entropy = harder to brute-force. Each additional character roughly adds log2(charset_size) bits. 60+ bits is generally considered strong.
Why is "Password1!" still rated Weak?
Common word + capitalization + symbol is a well-known pattern attackers target first. Entropy matters more than complexity requirements.