Password Strength Checker 🔒 Runs locally in your browser — nothing is uploaded.

Check a password's entropy, estimated crack time, and common weaknesses.

🔒 This password is analyzed entirely on your device, inside your browser tab. It is never sent anywhere — not over the network, not to our servers, not to any analytics. Closing this tab leaves no trace of it.
Start typing above to see a live strength analysis.

About this tool

This tool estimates password strength with the classic "charset to the power of length" heuristic: it looks at which character classes you actually used (lowercase, uppercase, digits, symbols, or other Unicode characters), adds up how big that combined alphabet is, and computes entropy as `length × log2(charsetSize)`. From that entropy it derives a rough crack-time estimate, assuming an attacker with stolen password hashes running roughly 10 billion guesses per second on modern GPU hardware — a commonly cited benchmark for fast, unsalted hash algorithms.

This is a deliberately simplified model, not a substitute for a research-grade estimator like zxcvbn: it does not know that "Password1!" is a well-worn pattern, or that "qwerty123" combines two things a cracker's dictionary already has memorized. To compensate a little, this tool also checks the password against a short list of extremely common passwords and a few obvious patterns (keyboard walks, sequential runs, repeated characters) and calls those out directly, on top of the entropy score.

Nothing you type here is ever sent anywhere. The analysis runs with plain JavaScript in this browser tab only — there is no network request involved, so it is safe to test your real passwords if you want an honest read on their strength.

Frequently asked questions

Is this as accurate as zxcvbn or other pattern-matching checkers?

No — this uses a simplified charset-based entropy formula plus a small common-password list, which is a reasonable rough gauge but doesn't model real-world cracking patterns as thoroughly as dedicated libraries like zxcvbn do (which analyze dictionary words, l33t-speak substitutions, dates and keyboard patterns much more deeply). Treat this tool's rating as a helpful estimate, not a definitive security audit.

Should I use a password manager instead of memorizing strong passwords?

Yes, generally — a password manager lets you use a long, unique, random password for every single account (which this tool would rate Very Strong) without needing to memorize any of them, and it removes the temptation to reuse passwords across sites, which is one of the biggest real-world security risks.