Password strength tester

Type a password to see an estimate of its strength and crack time. It's checked locally — never sent anywhere.

How to use the password strength tester

  1. Type a password (or one of similar style) into the box.
  2. Read the strength rating and estimated crack time.
  3. Lengthen it or use a passphrase if it's weak.

How this estimate works

Strength is estimated from length and the character variety used, expressed as bits of entropy, with an offline crack-time estimate at ~10 billion guesses/second. It runs entirely in your browser — nothing is transmitted — but the safest habit is to test a password of similar style rather than one you actively use. Need a stronger one? Generate a random password or a passphrase.

Code & API examples

Use this from the command line or your code.

Python (zxcvbn)
# pip install zxcvbn
from zxcvbn import zxcvbn
print(zxcvbn('correct horse battery staple')['guesses'])

See all endpoints at /api/tools/.

Frequently asked questions

The check runs entirely in your browser and nothing is transmitted. Still, the safest habit is to test a password of similar style rather than one you actively use.

16 characters or more for a random password, or 5–6 random words for a passphrase. Length matters more than swapping letters for symbols.
Related tools
Strong password generator Passphrase generator (diceware) Hash generator (SHA-256 & more)
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