Password Generator

For anything stored in a password manager, use 16 to 24 random characters, which lands well above 100 bits of entropy. For a memorized master password, use a passphrase of six random EFF-list words, about 78 bits. Consumer GPUs now test tens of billions of guesses per second against stolen fast hashes, so the old 8-character advice is obsolete.

Because this tester is honest. Many checkers multiply length by character-pool size, which assumes every character was chosen at random; human passwords never are. This page analyzes typed passwords with zxcvbn, the estimator built on tens of thousands of real common passwords, names, words, dates and keyboard patterns, and reports estimated guesses rather than a flattering exact-looking bit count. A famous phrase like "correct horse battery staple" is rated as the known phrase it is, not as 165 bits of randomness.

Generated secrets show exact entropy, because this page controls the randomness that made them: the number is a property of the generation procedure, including the required-class constraint. Typed passwords show an estimate, because no one can compute exact entropy for text a human made up. Treating those two as the same number is how weak passwords get called Excellent.

It depends on where the randomness comes from and where the password goes. This generator runs entirely in your browser using crypto.getRandomValues, the same cryptographic source your browser uses for TLS, and nothing is transmitted or stored. Avoid generators that produce passwords on a server, since you cannot verify they were never logged. This page keeps working with the network unplugged.

Use random character passwords for accounts a password manager fills in for you, since memorability does not matter and they pack more entropy per character. Use passphrases for the few secrets you must type from memory: your manager master password, device login and disk encryption. Six random words from the EFF 7,776-word list give about 78 bits and are far easier to recall than ten random symbols.

It uses k-anonymity. Your browser hashes the password with SHA-1 locally, then sends only the first five characters of the 40-character hash to the Have I Been Pwned range API, with response padding enabled so even the size of the response reveals nothing about which prefix was asked. The server returns hundreds of candidate hashes and your browser looks for a match locally. The service never sees your password or enough of the hash to identify it.

Yes. The single biggest win in personal security is a unique random password for every account, and that is only practical with a manager. When one site is breached, credential-stuffing bots replay the leaked email and password pair against hundreds of other services within hours. Unique passwords make the stolen pair worthless everywhere else and contain the damage to a single account.

Characters like capital I, lowercase l, the digit 1, capital O and zero look identical in many fonts, and brackets or pipes are easy to mistype. Excluding them helps when a password will be read aloud, printed, or typed by hand into a TV, router or console. The entropy cost is tiny, roughly a fifth of a bit per character, so leave them in for manager-stored passwords.