UsefulTab
Password Strength Checker
Estimate a password's strength and entropy — entirely offline.
Type a password to check its strength
You'll see a strength rating, an entropy estimate, an approximate crack time, and specific tips — all computed in your browser.
Runs entirely in your browserCheck password strength, privately
Type or paste a password and get a live strength rating based on its length and the variety of character types, expressed as an entropy estimate in bits and a rough offline crack-time. The checker also flags common weaknesses — too short, only one character class, obvious sequences or repeats. Because everything runs in your browser, the password you enter is never transmitted or stored; this is a private, offline estimate, not a breach lookup.
Common questions
How is strength measured?
It estimates entropy in bits from the password length and the size of the character set it draws on (lowercase, uppercase, digits, symbols), then adjusts down for obvious patterns like sequences ('abcd', '1234') and repeated characters. More bits means exponentially more guesses to crack.
What does the crack-time estimate mean?
A rough guide assuming a fast offline attacker trying about ten billion guesses per second against a well-hashed password. It is an order-of-magnitude estimate, not a guarantee — a password reused across sites can be compromised regardless of its strength.
Does this check if my password was leaked?
No. It measures theoretical strength only and never contacts any server or breach database. To check for known breaches you would need an online service; this tool deliberately stays fully offline for privacy.
Is my password uploaded anywhere?
No. The password is analysed entirely in your browser with JavaScript. It is never sent over the network, saved, or logged — it exists only in the page while you are on it.