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Password Strength Checker
Check the strength of a password on a 5-level scale and get improvement tips.
Overview
Checks the strength of an entered password.
Beyond character variety and length, it accounts for lists of commonly used passwords, dictionary words, keyboard patterns (like qwerty), sequences, dates, and repeated patterns, and displays a 5-level strength rating based on the estimated number of guesses needed to crack it.
If the password is rated weak, specific suggestions for improvement are also shown.
The password you enter is never sent anywhere; all checking runs entirely in your browser.
Usage
- 1
Enter the password you want to check into the "Password" field.
- 2
As you type, the strength and estimated number of guesses are displayed.
- 3
If the strength is low, a warning and improvement suggestions are also shown.
- 4
Click "Show" to view the entered value as plain text.
Example
Input
password
Output
Strength: Very weak (this is a top-10 common password)
Use Cases
Checking the strength of a password you're about to set when signing up for a new service
Using it as a rough guide when deciding on an internal password policy
Confirming that a value created with a password generator has the expected strength
FAQ
Is the password I enter sent anywhere?
No. Checking runs entirely in your browser, and nothing is sent to or stored on an external server.
Does using more character types or a longer password always increase the strength?
Not necessarily. A password like "Password123" includes uppercase, lowercase, and digits and is reasonably long, but is still rated weak because it follows a common pattern. This tool uses zxcvbn, an industry-standard password strength estimation algorithm developed by Dropbox, which accounts for lists of common passwords, dictionary words, keyboard patterns, and more for a more practical evaluation.
What does "estimated guesses" mean?
It's the estimated number of attempts an attacker would need to guess the password, expressed as a power of 10 (log10). A larger value means it is theoretically harder to crack.
Notes
Strength is evaluated using zxcvbn, an open-source library from Dropbox.
Some feedback messages that don't have a prepared Japanese translation may be shown in English.
Related Tools
Generate multiple passwords by specifying character types and length.
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Generate a bcrypt hash from a password or other text, and verify it against an existing hash.