A comprehensive, real-time password strength analyzer built with vanilla HTML, CSS, and JavaScript. This tool helps users create secure passwords by providing instant feedback, strength scoring, and security recommendations based on NIST guidelines and cybersecurity best practices.
- Real-time Password Analysis: Instant feedback as you type
- Strength Meter: Visual progress bar with color-coded strength levels
- Entropy Calculation: Mathematical strength assessment using entropy formula
- Pattern Detection: Identifies common weak patterns and dictionary words
- Time-to-Crack Estimation: Shows estimated time to crack password
- Password Visibility Toggle: Show/hide password with eye icon
- Interactive Checklist: Real-time requirements validation
- Responsive Design: Works on desktop and mobile devices
- Modern UI: Clean, professional interface with smooth animations
- Dark Mode Ready: Prepared for dark theme implementation
- NIST Compliance: Based on latest NIST password guidelines
- Common Password Detection: Checks against database of weak passwords
- Character Set Analysis: Evaluates use of different character types
- Length Requirements: Enforces minimum length recommendations
- Pattern Recognition: Detects keyboard patterns and sequences
- Password Generator: Create strong passwords with customizable options
- Copy to Clipboard: Easy password copying functionality
- Security Tips: Educational content about password best practices
- Strength Recommendations: Specific suggestions for improvement
The analyzer evaluates passwords based on these criteria:
| Criterion | Requirement | Points |
|---|---|---|
| Length | 8+ characters (12+ recommended) | 25% |
| Uppercase Letters | A-Z | 20% |
| Lowercase Letters | a-z | 20% |
| Numbers | 0-9 | 15% |
| Special Characters | !@#$%^&*()_+-=[]{}etc. | 15% |
| No Common Patterns | Avoid dictionary words, sequences | 5% |
| Level | Score Range | Color | Security Level |
|---|---|---|---|
| Very Weak | 0-30% | 🔴 Red | Easily cracked in seconds |
| Weak | 31-50% | 🟠 Orange | Could be cracked in minutes |
| Medium | 51-70% | 🟡 Yellow | Moderate security, hours to crack |
| Strong | 71-85% | 🟢 Light Green | Good security, days to crack |
| Very Strong | 86-100% | 🟢 Dark Green | Excellent security, years to crack |
The strength score is calculated using the entropy formula:
E = L × log₂(R)
Where:
- E = Entropy (bits)
- L = Password length
- R = Character set size (lowercase + uppercase + digits + symbols)
- Numbers (0-9): 10 characters
- Lowercase letters (a-z): 26 characters
- Uppercase letters (A-Z): 26 characters
- Special symbols: 32 characters
- Total possible: 94 characters
Based on modern hardware capabilities:
- Assumes 1 billion guesses per second
- Calculates expected time to crack (50% probability)
- Formula:
2^(entropy-1) / guesses_per_second
password-strength-analyzer/
├── index.html # Main HTML structure
├── style.css # Styling and animations
├── app.js # JavaScript functionality
├── README.md # Project documentation
└── assets/
└── icons/ # UI icons and graphics
- Modern web browser (Chrome, Firefox, Safari, Edge)
- No server setup required - runs entirely client-side
-
Clone the repository
git clone https://github.com/yourusername/password-strength-analyzer.git cd password-strength-analyzer -
Open the application
# Option 1: Open directly in browser open index.html # Option 2: Serve locally (optional) python -m http.server 8000 # Then visit http://localhost:8000
-
Start analyzing passwords!
- Enter a password in the input field
- Watch real-time strength feedback
- Follow recommendations to improve security
<!-- Include in your HTML -->
<script src="app.js"></script>
<link rel="stylesheet" href="style.css">
<!-- The analyzer will automatically initialize -->// Customize strength criteria
const analyzer = new PasswordAnalyzer({
minLength: 12,
requiredTypes: ['upper', 'lower', 'number', 'symbol'],
commonPasswords: customPasswordList
});const config = {
minLength: 8, // Minimum password length
recommendedLength: 12, // Recommended length
maxLength: 64, // Maximum allowed length
strengthLevels: 5, // Number of strength levels
realTimeValidation: true, // Enable real-time checking
showEntropy: true, // Display entropy score
showTimeToCrack: true // Show crack time estimation
};The CSS uses CSS custom properties (variables) for easy theming:
:root {
--primary-color: #4f46e5;
--success-color: #10b981;
--warning-color: #f59e0b;
--danger-color: #ef4444;
--background-color: #ffffff;
--text-color: #1f2937;
}- Custom validation rules: Extend the
validatePassword()method - New strength criteria: Modify the
calculateStrength()function - Additional UI elements: Update HTML structure and CSS
| Browser | Version | Support |
|---|---|---|
| Chrome | 60+ | ✅ Full |
| Firefox | 55+ | ✅ Full |
| Safari | 12+ | ✅ Full |
| Edge | 79+ | ✅ Full |
| IE | 11+ |
- Length over complexity: Longer passwords are generally more secure
- Unique passwords: Use different passwords for each account
- Password managers: Consider using tools like Bitwarden or 1Password
- Two-factor authentication: Add an extra layer of security
- Regular updates: Change passwords if accounts are compromised
This tool follows the latest NIST Special Publication 800-63B guidelines:
- Minimum 8 characters (recommends 12+)
- No mandatory periodic changes
- Allow all printable ASCII characters
- Check against common password lists
- Support password managers and copy/paste
We welcome contributions! Here's how you can help:
- Use GitHub Issues to report bugs
- Include browser version and steps to reproduce
- Provide screenshots if applicable
- Fork the repository
- Create a feature branch (
git checkout -b feature/amazing-feature) - Commit your changes (
git commit -m 'Add amazing feature') - Push to the branch (
git push origin feature/amazing-feature) - Open a Pull Request
- Follow existing code style
- Add comments for complex logic
- Test in multiple browsers
- Update documentation as needed
This project is licensed under the MIT License - see the LICENSE file for details.
MIT License
Copyright (c) 2025 Password Strength Analyzer
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
- NIST for password security guidelines
- Dropbox zxcvbn for inspiration on password strength algorithms
- Web security community for research and best practices
- Open source contributors who make projects like this possible
- Documentation: Check this README and code comments
- Issues: GitHub Issues
- Discussions: GitHub Discussions
- Email: support@passwordanalyzer.com
- Initial release
- Real-time password analysis
- Entropy calculation
- Modern responsive UI
- Password generator
- Security tips and recommendations
- Download or clone this repository
- Open
index.htmlin your web browser - Start typing a password to see real-time feedback
- Follow the suggestions to create a stronger password
- Use the generator if you need help creating passwords
That's it! No installation, no setup, no dependencies. Just open and start creating secure passwords.
Made with ❤️ for a more secure internet