Password Strength Checker
Analyze password entropy and crack time locally. Your password never leaves your device.
Vulnerability Analysis
- Start typing to see analysis.
How Password Entropy Works
This tool analyzes your password entirely in your browser using mathematical entropy. Entropy represents the unpredictability of a password based on its length and the pool of characters used (lowercase, uppercase, numbers, and symbols).
What is a good entropy score?
- < 40 bits: Extremely weak. Can be cracked instantly.
- 40 - 60 bits: Weak. Vulnerable to dictionary and brute-force attacks.
- 60 - 80 bits: Strong. Safe for most online accounts.
- > 80 bits: Very strong. Recommended for sensitive data (banking, master passwords).
Privacy Guarantee
Your keystrokes are processed strictly via client-side JavaScript. This tool does not make any network requests. Your password is never logged, stored, or transmitted.
What is Password Entropy?
Password entropy is a measurement of how unpredictable a password is. A higher entropy means a password is mathematically harder to crack. Passwords with low entropy can be cracked instantly by modern GPUs, while high-entropy passwords (over 80 bits) can withstand brute-force attacks for trillions of years.
Frequently Asked Questions
How does this tool estimate "time to crack" a password?
It calculates the password's entropy (based on length and character variety), then estimates how long a brute-force attack would take against that keyspace at a given guesses-per-second rate — this is an estimate, not a guarantee, since real attacks often use smarter methods than pure brute force.
Is a longer password always stronger than a more complex short one?
Generally yes — length has a bigger multiplicative effect on entropy than added complexity. A 16-character lowercase-only password is often stronger against brute force than an 8-character password with symbols.
Does this tool check my password against known data breaches?
No — this tool only analyzes structural strength (length, character variety, common patterns) locally in your browser. It does not check against breach databases, so a password can score well here but still be one that's been leaked elsewhere.
Is my password sent anywhere when I type it in?
No, all analysis happens entirely client-side in your browser — your password is never transmitted over the network or stored.
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