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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
- Enter the password you want to check into the "Password" field.
- As you type, the strength and estimated number of guesses are displayed.
- If the strength is low, a warning and improvement suggestions are also shown.
- 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.
Generate multiple random strings by specifying character types and length.
Generate a bcrypt hash from a password or other text, and verify it against an existing hash.