Password Strength Checker
Check how strong your password is. Everything runs locally in your browser.
Your password is the gateway to your digital life. Our password strength checker provides a comprehensive, real-time analysis of any password you enter. It evaluates multiple factors including length, character diversity, Shannon entropy, and estimated brute-force crack time. The tool runs entirely in your browser, meaning your password is never sent to any server or stored anywhere. Whether you are a developer building authentication systems, a security professional auditing credentials, or simply someone who wants to ensure their accounts are protected, this tool gives you the insights you need. The strength meter provides an intuitive visual indicator, while the detailed metrics give you the technical depth to understand exactly why a password is strong or weak. Use it to test passwords before committing them to your accounts, or to educate users about what makes a password secure. The character category analysis shows you exactly which types of characters you are using and which you are missing, making it easy to improve your password incrementally.
How to Use This Tool
- 1. Enter your password in the secure input field
- 2. Toggle visibility to verify your password if needed
- 3. Watch the animated strength bar update in real-time
- 4. Review the strength rating from Very Weak to Very Strong
- 5. Check entropy bits and estimated crack time
- 6. Use character category chips to identify improvements
Why Use This Tool
- Complete privacy with zero server communication
- Real-time analysis as you type each character
- Professional-grade Shannon entropy calculation
- Realistic brute-force crack time estimation
- Visual strength meter with color coding
- Character category breakdown for targeted improvement
Frequently Asked Questions
Is my password sent to any server?
Absolutely not. All analysis happens locally in your browser using JavaScript. Your password never leaves your device.
How is the strength score calculated?
The score is based on Shannon entropy, which considers password length and the size of the character pool (lowercase, uppercase, digits, symbols, spaces).
What crack time assumption do you use?
We assume 10 billion guesses per second, representing a powerful GPU cluster attacking a fast hash function like MD5.
What is a good password strength?
Aim for "Strong" or "Very Strong" ratings, which correspond to 60+ bits of entropy. This typically requires 12+ characters with mixed character types.
Can I use this tool offline?
Yes. Once the page is loaded, all functionality works without an internet connection.
Does this work on mobile devices?
Yes. The tool is fully responsive and works on all modern mobile browsers.