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Password Strength Checker

Analyze your password's strength, entropy, and estimated crack time. Get specific suggestions to make it stronger. Your password never leaves your browser.

Enter a password to check its strength
0
Characters
0
Entropy (bits)
0/5
Score
—
Est. Crack Time
Criteria
✓ At least 12 characters
✓ Uppercase letters (A–Z)
✓ Lowercase letters (a–z)
✓ Numbers (0–9)
✓ Special characters (!@#$...)
✓ No long repeated patterns
✓ Not a common password
✓ 16+ characters (excellent)
Suggestions
  • Enter a password above to receive personalized suggestions.

About Password Strength Checker

This tool analyzes your password locally in your browser — it is never transmitted to any server. It checks length, character variety, entropy (randomness), and known weak patterns to give you an accurate strength assessment and actionable improvement tips.

What Makes a Strong Password?

A strong password is long (16+ characters), uses a mix of character types (uppercase, lowercase, numbers, symbols), avoids dictionary words, and contains no predictable patterns like "123" or "aaa".

Frequently Asked Questions

Yes. The password is analyzed entirely in your browser using JavaScript. It is never sent to any server, never logged, and never stored anywhere. You can verify this by disconnecting from the internet and the tool will still work perfectly.
Entropy measures the unpredictability (randomness) of a password in bits. It's calculated as log₂(character_pool_size^length). Higher entropy means more possible combinations for an attacker to guess. 50+ bits is good; 80+ bits is strong; 100+ bits is excellent.
Crack time is estimated based on entropy and assumes an offline brute-force attack at 10 billion guesses per second — the speed of a modern GPU cluster. Online attacks are much slower (100–1000 guesses/second) due to rate limiting.
A strong password is hard to guess or crack. A secure password is also unique (not reused across sites), stored safely (in a password manager), and changed if the site it was used on suffers a data breach. Strength is necessary but not sufficient for security.

About Password Strength Checker

The Password Strength Checker analyzes your password in real time and estimates how long it would take to crack using brute-force methods. It identifies weaknesses and gives actionable suggestions for improvement — all without ever sending your password to a server.

How to Use

  1. Type your password in the input field.
  2. The strength meter updates instantly, showing: Weak, Fair, Strong, or Very Strong.
  3. Read the analysis for specific weaknesses (too short, no symbols, repeated characters, etc.).
  4. Check the estimated crack time to understand the real-world security of your password.

How It Works

The tool evaluates password entropy based on character set size and length, then runs pattern checks (common words, keyboard patterns, repeated characters). Crack time is estimated assuming 10 billion guesses per second (modern GPU attack speed).

Example

password123 — Weak. Cracks in milliseconds.
Tr0ub4dor&3 — Strong. Estimated years to crack.
correct-horse-battery-staple — Very Strong. A passphrase beats most complex short passwords.

Frequently Asked Questions

Absolutely not. Your password is analyzed entirely in your browser using JavaScript. It is never sent to any server, logged, or stored in any way. You can safely test real passwords.
Security experts recommend at least 16 characters. Longer passwords are exponentially harder to crack. A 20-character random password is far stronger than an 8-character password with special characters.
Often yes. A phrase like "correct-horse-battery-staple" (28 chars) is both memorable and extremely hard to brute-force, while a complex 8-character password like "P@ss123!" is much weaker due to its short length.
Yes, highly recommended. Password managers (1Password, Bitwarden, Dashlane) generate and store unique random passwords for every site, so you only need to remember one master password.