Password strength checker
Generated in your browser · never sent, never stored
This measures one thing: how many guesses an attacker would need if your password really were random. It reads the character classes present and the length, and reports the entropy that combination could carry at best.
How to check a password
Be clear about the limitation, because most strength meters are not. This is an upper bound, not a score. "Password1!" contains four character classes across ten characters and scores as though it were random, when in reality it appears near the top of every cracking dictionary and falls in under a second. No meter that looks only at the characters can tell the difference. The number is meaningful for a password you generated randomly and misleading for one you invented — which is the strongest argument for not inventing them.
Questions
No. There is no network request on this page at all. The calculation is a few lines of arithmetic running locally.
Because the calculation assumes randomness. A dictionary word with a capital and a digit fits the pattern attackers try first, and no character-counting meter can see that.
No. That would require sending something to a service, and this page does not make requests. Your password manager or browser can do that check.
Under 40 is weak, 60 is a sensible floor for an account that matters, and above 80 puts an offline attack out of practical reach.
Ten billion a second, which is roughly one modern GPU against a fast hash. Sites that hash properly are far slower to attack; the pessimistic number is the safer one to plan around.