Check Your Password Strength
Entropy & crack-time estimate
- Empty password.
- Include a digit.
- Add a symbol (!@#$%).
What is Password Strength Checker?
Analyse a password's entropy and estimated brute-force crack time. The report shows entropy in bits, the character-class pool used, and a rough crack-time estimate based on 10^10 guesses per second (a reasonable offline-attack rate against a fast hash like SHA-256). Flags common patterns; single-character repeats, top-password-list matches; and gives concrete improvement suggestions.
How do I use Password Strength Checker?
- Type or paste the password (use the Reveal toggle if typing).
- Read the strength score, entropy, and crack-time estimate.
- Follow the suggestions to improve weak passwords.
When should I use Password Strength Checker?
Password Strength is a heuristic. For a production-quality audit, zxcvbn is the gold standard (it's ~800 KB and we chose not to bundle it). To generate a new strong password instead of checking one, use Password Generator.
Frequently asked questions
How is strength calculated?
Using zxcvbn; the same library LinkedIn, Dropbox, and 1Password use. It estimates the number of guesses a realistic attacker would need, factoring in dictionary words, common patterns, repeats, and keyboard sequences.
Is my password sent anywhere?
No. zxcvbn runs entirely in your browser; the password is never transmitted. Typed passwords are not saved in local storage either.
What score should I aim for?
Score 4 (strong) or better for anything protecting financial, health, or sensitive accounts. Score 3 is acceptable for low-stakes logins if paired with a second factor.
Is my file uploaded anywhere?
No. Everything runs in your browser. Your files never leave your device, and there is no server component for this tool.
Tools that pair well with Password Strength Checker
- Password Generator strong, customizable passwords, free and in your browser.
- Hash Generator md5, sha-256, sha-512, free and in your browser.
- HMAC Generator hmac with any hash, free and in your browser.
- Random Number Generator secure random generator, free and in your browser.