Password Strength Checker

Against the criteria that actually predict resistance to guessing: length, the variety of character types present, and whether the password contains common patterns. Length carries the most weight, because it is what grows the search space fastest.

Here, yes, because nothing is transmitted. The analysis runs entirely in JavaScript on your device and your password never touches a network. As a general habit, though, be wary: most online checkers send what you type to a server, and there is no way to tell from the page which kind you are using.

Length only helps when the content is unpredictable. A long phrase from a song, a keyboard run, or a name with a year appended is in every attack dictionary, so its effective strength is far lower than its character count suggests. Attackers guess patterns, not random characters.

Barely. Every cracking tool has applied those rules for decades, so P@ssw0rd is only marginally harder than password. The gain is a rounding error next to simply making the password longer and less predictable.

Usually, provided the words are chosen at random rather than by you. Four or five random words give a large search space and are far easier to remember and type than a short string of symbols. A phrase you composed yourself is much weaker, because human word choice is highly predictable.

Make it longer before you make it more complicated, and let a password manager generate it so it is genuinely random. Then check whether you have used it anywhere else, because reuse turns one weak password into a problem across every account that shares it.