Password Strength Checker

The Password Strength Checker rates any password you type and shows roughly how long it would survive a real cracking attack — without the password ever leaving your device. The analysis runs entirely in your browser as local JavaScript: nothing is uploaded, logged, or sent to a server, which is why you can safely test a live production password here. As you type, the tool measures the factors that actually decide strength: total length, the mix of lowercase, uppercase, digits and symbols, the size of the resulting character pool, and the weakening patterns that make a "complex-looking" password easy to guess — dictionary words, keyboard runs like "qwerty", repeated characters, sequential digits, and predictable leet substitutions such as "@" for "a" or "0" for "o". From that it computes entropy in bits, then discounts it when patterns are detected, and converts the result into a readable crack time under a realistic offline GPU attack guessing billions of candidates per second, ranging from "instantly" to "centuries". A colored meter and a one-word verdict — weak, fair, strong, or very strong — refresh on every keystroke, and specific tips appear beside them: "add 4 more characters" or "avoid the word 'summer'", so you know exactly what to change rather than staring at a bare score. This helps in concrete moments: creating an account and wanting to beat a site's vague built-in meter, auditing an old password you still reuse, showing a family member or colleague why "Password1!" cracks in seconds, or building a passphrase and confirming that length beats symbol soup — it usually does. A four-word phrase like "correct-horse-battery-staple" outscores a short scrambled string, and because the check is instant and offline you can watch the crack-time estimate climb as you extend a phrase. The numbers are guidance, not guarantees, but they mirror how attackers with modern hardware actually work, which makes this a practical habit for anyone juggling more than a handful of logins.