Password Strength Checker

What Is a Password Strength Checker?

A password strength checker is an educational tool designed to help you evaluate the potential security and resilience of your passwords against common attack methods, such as brute-force or dictionary attacks.

Our tool analyzes various characteristics of your input—including length, character variety, and predictable patterns—to provide an estimated strength score from 0 to 100.

How to Use This Tool

1. Enter your password: Type the password you wish to test into the secure input field above.
2. Review the instant score: Observe the 0-100 score and the visual strength meter.
3. Read the actionable feedback: The "Analysis" box will provide specific suggestions—such as adding length or avoiding sequential keys—to help you fortify the password.
4. Generate an alternative: If your password is weak, use the built-in Password Generator at the bottom of the tool to create a cryptographically secure alternative.
5. Clear when finished: Click the "Clear Input" button to completely reset the tool state.

Our Strict Privacy Guarantee

We believe that entering passwords into a website requires absolute trust. That is why this tool is built using a strict client-side architecture.

• No Server Transmission: The JavaScript analyzing your password runs entirely within your local web browser. Your keystrokes never leave your device.
• No Logging or Storage: We do not log your inputs, and we do not store them in cookies, local storage, or browser history.
• Offline Capability: Once this page loads, you can safely disconnect from the internet and the tool will continue to function flawlessly.

How We Calculate the Score

The algorithmic score is primarily driven by Estimated Entropy. Entropy measures the mathematical unpredictability of a string based on its length and the size of the character pool used (lowercase, uppercase, numbers, symbols).

However, pure entropy isn't enough. Our algorithm actively subtracts points if it detects human predictability:

• Repeated Characters: e.g., "aaaaaaa"
• Sequential Keys: e.g., "123456" or alphabetical sequences.
• Keyboard Patterns: e.g., "qwerty" or "asdfgh".
• Common Dictionary Passwords: Basic checks against universally weak passwords.

Important Limitations

While this tool provides a robust mathematical estimate, no automated checker can guarantee absolute security.

This checker cannot know if your password has been previously leaked in a third-party data breach. It also cannot know if the password relies on easily guessable personal information (like your pet's name or your birth year) that an attacker might find on your social media profiles.

The most secure password is one generated randomly by a password manager, which you have never used anywhere else.