Password Strength Checker — Free Test Password Security
Test password strength with entropy analysis and crack time estimation. Checks for common patterns, keyboard sequences, and dictionary words. Browser-based.
Features
- ✓Real-time password strength scoring from 0 (Very Weak) to 4 (Very Strong)
- ✓Entropy calculation based on character set size and password length
- ✓Estimated crack time using 10 billion guesses/second (modern GPU farm)
- ✓Detects common passwords from a built-in dictionary
- ✓Identifies keyboard patterns (qwerty, asdf, 123456)
- ✓Detects repeating and sequential character patterns
- ✓Catches leet-speak substitutions (p@ssw0rd → password)
- ✓Character composition breakdown (uppercase, lowercase, numbers, symbols)
- ✓Actionable improvement suggestions
- ✓Show/hide password toggle for safe testing
- ✓Copy password to clipboard with one click
- ✓All analysis runs locally — password never leaves your browser
How to Use
- 1Type or paste any password into the input field.
- 2Watch the strength bar update in real time as you type.
- 3Check the entropy score — higher bits mean stronger password.
- 4Read the estimated crack time to understand practical security.
- 5Review the composition breakdown to see character diversity.
- 6Follow the suggestions to improve weak passwords.
- 7Use the eye icon to toggle password visibility when testing.
- 8Try common passwords (like 'password123') to see how fast they're flagged.
- 9Compare different password strategies: length vs complexity.
- 10Use this tool alongside Password Generator to create and verify strong passwords.
Frequently Asked Questions
How is password strength calculated?
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Strength is based on entropy, which measures the randomness of your password. It considers character set size (lowercase, uppercase, numbers, symbols), password length, and penalizes common patterns like dictionary words, keyboard sequences, and repeated characters.
What is entropy in passwords?
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Entropy is measured in bits and represents how unpredictable a password is. A 12-character password with mixed character types typically has 70-80 bits of entropy. Higher entropy means more possible combinations, making brute-force attacks harder.
How long would it take to crack my password?
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The tool estimates crack time assuming 10 billion guesses per second (typical for a modern GPU farm). A 6-character password might be cracked instantly, while a 16-character random password would take centuries.
Is it safe to type my real password here?
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Yes. All analysis happens locally in your browser using JavaScript. Your password is never sent to any server, stored in cookies, or logged anywhere. You can even disconnect your internet and the tool still works.
What makes a password strong?
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A strong password is long (12+ characters), uses a mix of uppercase, lowercase, numbers, and symbols, and avoids dictionary words, personal information, and common patterns. Length is more important than complexity.
Why is my password flagged as weak even though it has symbols?
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Symbols alone don't make a password strong. If your password is short (under 8 characters) or uses common patterns (like 'P@ssw0rd'), it's still weak. The tool checks for dictionary words with leet-speak substitutions.
What's the difference between entropy and crack time?
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Entropy measures mathematical randomness (in bits). Crack time converts that into a practical estimate assuming current hardware capabilities. Two passwords can have similar entropy but different crack times if one uses common patterns.
Should I use a password manager?
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Yes. A password manager generates and stores unique, strong passwords for every account. You only need to remember one master password. This is far more secure than reusing the same password across sites.
How is this different from zxcvbn?
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zxcvbn (by Dropbox) uses a large dictionary database to check against known passwords. This tool uses a lighter approach with built-in pattern detection. For most users, the results are comparable. For maximum accuracy, use tools backed by zxcvbn.
Can I use this to test passphrases?
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Yes. Passphrases like 'correct horse battery staple' score well due to length, even without symbols. The tool evaluates total entropy, not just character variety. Long passphrases are often stronger than short complex passwords.
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