Free Strong Password Generator
Create strong random passwords, easy-to-type passphrases or PINs on your own device. See the real strength in bits of entropy, and test a password you already use.
Strong Password Generator: Create strong random passwords, easy-to-type passphrases or PINs on your own device. See the real strength in bits of entropy, and test a password you already use. It is free, needs no sign-up and runs in your browser. How to use it: 1) choose a random password, a passphrase or a PIN; 2) set the length or number of words and the character options; 3) copy a password and save it in your password manager. Passwords are made in your browser with crypto.getRandomValues, the cryptographically secure random number generator built into every modern browser. Rejection sampling removes the small bias that a simple remainder would add, so every character or word is equally likely.
How the password generator works
Passwords are made in your browser with crypto.getRandomValues, the cryptographically secure random number generator built into every modern browser. Rejection sampling removes the small bias that a simple remainder would add, so every character or word is equally likely. Nothing is sent to a server or saved, and the tool works offline.
Three modes
- Random password: 4 to 128 characters from upper case, lower case, numbers and symbols, with at least one of each type you tick. You can avoid look-alike characters such as l, 1, O and 0.
- Passphrase: 3 to 12 random words from the 2,048-word BIP39 list, with optional capitals, a number and a symbol. Easy to type on a phone and to remember.
- PIN: 4 to 12 random digits.
Strength and entropy
Strength is measured in bits of entropy: bits = length x log2(pool size) for passwords and words x 11 for passphrases. Under 40 bits is weak, 60 is fair, 80 and above is very strong. Crack time assumes an attacker making 10 billion guesses a second against a leaked, fast hash, and is an average.
Limitations
Entropy only measures randomness when the password really was random. The “test a password” box is a rough estimate based on length, character types and common patterns; it cannot know every leaked password. Never reuse passwords, turn on two-factor login and keep passwords in a password manager.
Password Generator FAQs
Is it safe to use an online password generator?
This one is safe because the password is created inside your own browser with its secure random generator, and nothing is sent or stored anywhere. You can even disconnect from the internet and it still works. Copy the password straight into your password manager or the site you are signing up to.
How long should a strong password be?
For accounts protected by a password manager, use 16 or more random characters, which gives over 100 bits of entropy. For a password you need to remember and type, a passphrase of five or six random words is strong and easier. Anything under 12 characters is too short today.
What is a passphrase and is it secure?
A passphrase is several random words joined together, such as Lock-Immense-Buffalo-Draft1-Plate. Picked at random from 2,048 words, each word adds 11 bits of entropy, so five words give about 55 bits and six give 66. It is secure as long as the words are chosen randomly, not by you.
What does entropy in bits mean?
Entropy measures how many guesses an attacker needs. Each extra bit doubles the work. A 40-bit password has about one trillion combinations, which fast cracking hardware can try quickly. An 80-bit password has a trillion times a trillion more, which is out of reach for any known attacker.
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