Password Strength Analyzer
Test your password security instantly. All checks run locally—your password never leaves your device.
Requirements
Suggestions:
What Makes a Strong Password?
A strong password should be at least 12 characters long and include a mix of uppercase letters, lowercase letters, numbers, and special characters.
Avoid: Common words, personal information, sequential patterns (123456, abcdef), and repeated characters.
Best practice: Use a password manager to generate and store unique passwords for each account.
Password Security Best Practices
- ✓ Use 16+ characters for sensitive accounts
- ✓ Use a unique password for every account
- ✓ Use a password manager (Bitwarden, 1Password)
- ✓ Enable 2FA/MFA wherever possible
- ✓ Consider passphrases (correct horse battery staple)
- ✗ Use personal info (birthday, pet names)
- ✗ Use dictionary words without modification
- ✗ Use sequential patterns (123456, qwerty)
- ✗ Reuse passwords across multiple sites
- ✗ Share passwords via email or text
Weak vs Strong Password Examples
| Password | Strength | Why? |
|---|---|---|
| password123 | WEAK | Common word + simple number sequence |
| JohnSmith1990 | WEAK | Personal info (name + birth year) |
| P@ssw0rd! | FAIR | Common substitution pattern (a→@, o→0) |
| Tr0ub4dor&3 | GOOD | Mixed chars, but pattern-based |
| correct-horse-battery-staple | STRONG | Long passphrase, easy to remember |
| xK9#mP2$vL7@nQ4 | STRONG | Random, high entropy, manager-generated |
How Attackers Crack Passwords
Dictionary Attack
Tries common words, phrases, and previously leaked passwords. Modern tools test millions of combinations per second.
Brute Force Attack
Systematically tries every possible combination. GPUs can test billions of hashes per second for weak algorithms.
Credential Stuffing
Uses leaked username/password pairs from breaches to try logging into other sites. This is why password reuse is dangerous.
Rainbow Tables
Pre-computed tables mapping hashes to passwords. Defeated by salted hashing (modern standard).
Privacy First
This password checker runs entirely in your browser. Your password is never sent to any server or stored anywhere. All analysis happens locally on your device using JavaScript.
Frequently Asked Questions
Is my password safe when using this tool?
Yes! Your password never leaves your device. This tool uses the zxcvbn library which runs entirely in your browser using JavaScript. No data is sent to any server, making it completely safe to test even your actual passwords.
What is zxcvbn and how does it work?
Zxcvbn is a password strength estimator developed by Dropbox. Unlike simple checkers that only look for character types, zxcvbn:
- Recognizes common words, names, and patterns
- Detects keyboard patterns (qwerty, 123456)
- Identifies date formats and sequences
- Estimates actual crack time based on attack scenarios
Should I use a password manager?
Absolutely! Password managers are recommended by security experts because they:
- Generate truly random, high-entropy passwords
- Store unique passwords for every account
- Auto-fill credentials (preventing phishing)
- Alert you to breached or weak passwords
Popular options: Bitwarden (free), 1Password, Dashlane, KeePassXC (offline)
What is two-factor authentication (2FA)?
2FA adds a second verification step beyond your password. Even if someone steals your password, they can't access your account without the second factor:
- TOTP apps (Google Authenticator, Authy) - Recommended
- Hardware keys (YubiKey, Titan) - Most secure
- SMS codes - Better than nothing, but vulnerable to SIM swapping
How do I know if my password was in a breach?
You can check if your email or password has been exposed in known breaches:
- Have I Been Pwned (haveibeenpwned.com) - Check emails and passwords
- Firefox Monitor - Mozilla's breach notification service
- Google Password Checkup - Built into Chrome
If your password appears in a breach, change it immediately on all sites where you used it.