パスワード生成

What actually makes a password hard to crack is its randomness and length, not clever substitutions. A long password drawn from a truly random source has so many possible combinations that brute-forcing it is infeasible; a short "complex" one with predictable patterns is not.

Length adds security faster than any single symbol does, because every extra random character multiplies the number of possibilities an attacker must try.

This generator builds passwords from the character sets you enable, lowercase, uppercase, numbers and symbols, and guarantees at least one character from each set you turn on. It uses your browser's cryptographically secure random generator, and a strength estimate updates as you adjust the options.

As a rule of thumb, use at least 16 characters for everyday accounts and more for important ones like email or banking. If you prefer something you can type or say aloud, a long passphrase of several random words is also strong; the key in every case is randomness and length, not memorable but guessable tricks.

Store each generated password in a password manager rather than trying to remember it, and never reuse the same password across sites. A unique random password per account means a leak at one service cannot unlock the others.

For a password tool, running on-device is not a nice-to-have but a requirement: a generator that sent your new password to a server would defeat its own purpose. Here, generation is fully client-side, so the password is never transmitted, stored or logged, and you can copy it with one click.