What it does
The password generator makes random passwords from the characters you choose:
- Uppercase A–Z and Lowercase a–z: the 26 letters of the English alphabet, in capitals and in small letters.
- Digits 0–9.
- Symbols: the 32 punctuation marks of ASCII, such as !, ?, #, % and @.
Each password holds at least one character of every set you turn on. Above the passwords, a line gives their computed entropy: how many passwords the generator could have made with your settings, in bits.
The page opens with five passwords of 16 characters from all four sets on your first visit, then your last choices. Change an option and new passwords appear straight away.
How to use it
- Set Length, from 4 to 128 characters.
- Turn the sets you want on or off; at least one must be on.
- Under More options, set How many, from 1 to 50, and turn on Avoid look-alike characters to leave out characters that are easy to misread, such as 0 and O.
- Select Copy all for every password, one per line, or Copy next to a single one.
- Select Regenerate, or press Ctrl+Enter (⌘+Enter on a Mac), for new passwords with the same options.
The generator remembers your choices on this device, never the passwords.
How it works
- Random characters: each character comes from one random byte from your browser’s cryptographic random number generator. A byte has 256 values, which don’t divide evenly into 94 characters, so the generator keeps only the bytes 0 to 187, two full rounds of the 94, and skips the rest. The remainder after dividing the byte by 94 picks the character, so every character has exactly the same chance. Fewer characters work the same way: with 87, the bytes from 174 up are skipped.
- One of each set: a password that misses a set you chose is thrown away and drawn again in full. Swapping in a missing character instead would make some passwords more likely than others.
- Computed entropy: the generator counts the passwords it can make: every string of the chosen length from your characters, less those that miss a set, counted exactly by inclusion–exclusion. For 16 characters from all 94, 82.3% of all strings hold every set, so the count works out at 104.59 bits, shown rounded down as About 104 bits.
Good to know
- Length runs from 4 to 128 characters, and How many from 1 to 50 passwords.
- With 4 characters and all four sets on, each password has exactly one character of each set.
- The 32 symbols are listed under the Symbols checkbox. Some sites don’t accept every symbol; turning Symbols off leaves them all out.
- The computed entropy describes a password exactly as it was made. Edit a character by hand and the figure no longer applies.
Privacy
Everything is made in your browser, on your device. The passwords aren’t uploaded, stored or sent anywhere, and each visit makes new ones. Only your choices for the length, the sets, how many and look-alikes are kept, in this browser’s storage, so the page can show them again.