Password Strength Checker — Free Entropy-Based Real-Time Analysis
Analyze password strength with entropy-based scoring. Get estimated crack time, improvement tips, and character analysis — your password is never sent to a server.
Frequently Asked Questions
Q. Is my password sent to a server?
Absolutely not. All analysis is processed directly in your browser. Your password never leaves your device.
Q. What is entropy?
Entropy measures a password's unpredictability in bits. The higher the value, the stronger the password. 128+ bits is practically uncrackable with current computing technology.
Q. How is estimated crack time calculated?
Based on a modern GPU performing 10 billion guesses per second. Real-world attacks are typically slower, so your password may be even safer.
Q. What makes a password secure?
At least 16 characters including uppercase, lowercase, numbers, and symbols. Avoid personal information (name, birthday) and dictionary words.
Q. Should I use a password manager?
Yes — to maintain strong, unique passwords for every site, a password manager (1Password, Bitwarden, etc.) is strongly recommended.
Q. Can I reuse passwords across sites?
Never. If one site is breached, all accounts using the same password become vulnerable to "credential stuffing" attacks.
How to Use
Type the password to analyze. (Never sent to a server)
The strength bar and level (Very Weak–Very Strong) update in real time.
Review entropy (bits), estimated crack time, and character composition analysis.
Follow the suggestions to strengthen your password.
Expert Knowledge: Password Strength Checker — Free Entropy-Based Real-Time Analysis
Password entropy is calculated using Shannon entropy: H = L × log₂(N), where L is length and N is character set size. Lowercase only gives N=26; combining uppercase, lowercase, digits, and symbols gives N≈94. NIST SP 800-63B (2017) guidelines recommend a minimum of 8 characters, Unicode support, and a length-over-complexity-rules policy. You can check if your password has been exposed using the Have I Been Pwned (HIBP) service.
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