Password Strength Checker
Instantly check how strong your password is. Get crack time estimates, pattern detection, and actionable suggestions — powered by Dropbox's zxcvbn algorithm. Your password never leaves your device.
Enter a password to check
Password never leaves your browser — all analysis runs locally.
Type a password above to see its strength score, crack time estimates, and improvement suggestions.
Frequently Asked Questions
- Is this password strength checker free?
- Yes, 100% free. No account, no sign-up, no limits.
- Is my password safe to enter here?
- Absolutely. All analysis runs entirely in your browser using JavaScript. Your password is never sent to any server, never logged, and never stored. You can even disconnect from the internet and it will still work.
- What algorithm does this use?
- This tool uses zxcvbn, the open-source password strength estimator created by Dropbox. It analyses over 30,000 common passwords, keyboard patterns, dates, names, and dictionary words to give you a realistic crack-time estimate — far more accurate than simple rules like 'must have a capital letter'.
- What is a good password strength score?
- A score of 3 (Strong) or 4 (Very Strong) is recommended. Scores of 0–2 mean the password could be cracked quickly by attackers. Aim for a random passphrase of 4+ words or a 16+ character mix of letters, numbers, and symbols.
- What do the crack time estimates mean?
- There are three scenarios: an online attack (throttled at 10 guesses/sec, like a login form), an offline slow-hash attack (10,000/sec, like bcrypt), and an offline fast-hash attack (10 billion/sec, like unsalted MD5). Most websites use bcrypt, so the offline slow estimate is the most realistic worst case.
- Does it work on mobile?
- Yes, works on all modern browsers including mobile Safari and Chrome on Android and iOS.