Password Strength Checker
Analyze password length, entropy, character diversity, and common weaknesses. Check password strength locally. Free, private, browser-based.
No sign-up • No server uploads • 100% browser-based
How It Works
1 Type Password
Enter a password in the input field. Analysis happens in real time as you type. Your password never leaves your device.
2 Analyze
Shannon entropy, character diversity, and length are calculated instantly. The tool checks against common passwords and patterns.
3 Improve
Review suggestions to make your password stronger. The crack time estimate shows how long a brute-force attack would take.
Frequently Asked Questions
How is password strength calculated?
The tool calculates Shannon entropy based on character diversity and length. It also checks against a list of common passwords, analyzes character types, and estimates crack time.
What is entropy in password strength?
Entropy measures the unpredictability of a password. Higher entropy means more possible combinations and stronger protection against brute-force attacks.
Is my password uploaded to a server?
No. All password analysis happens entirely in your browser. Your password never leaves your device.
What makes a password strong?
A strong password is at least 12-16 characters long, includes uppercase, lowercase, digits, and symbols, avoids dictionary words and common patterns, and has high entropy.
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