Password Security Checker
Check a Password's Real Security Against Known Weaknesses
Need to use Password Security Checker right now?
Real password security depends on more than meeting a site's complexity checklist — this checks against actual attacker techniques: leaked password lists, sequences, and repeated characters.
This check runs entirely in your browser — your password is never sent anywhere.
Features
- Runs entirely in your browser
- Privacy-first — your data is never uploaded
- Real-time, instant results
- 100% free, no sign-up required
- Works on desktop, tablet, and mobile
- No installation needed
Who uses this tool?
About Password Security Checker
Password strength meters built into signup forms are often shallow, checking only for length and a mix of character types without catching the patterns real attackers actually exploit — common leaked passwords, keyboard sequences, and repeated characters that dramatically weaken a password even when it technically satisfies every complexity rule.
This tool checks a password against several real weaknesses at once: raw entropy (based on length and character variety), whether it matches one of the most commonly leaked passwords ever recorded, whether it contains a keyboard or alphabetic sequence (like "qwerty" or "abc"), and whether it has three or more repeated characters in a row — all well-documented patterns that make a password meaningfully easier to guess.
The entropy calculation estimates how many possible passwords could exist given the password's length and which character types it uses — a rough but genuinely informative measure of brute-force resistance. A password can have decent raw entropy and still score poorly here if it matches a known-leaked password or contains an obvious pattern, since real attackers try those first, long before resorting to true brute force.
This is useful for checking a new password before committing to it, understanding specifically why a password is considered weak (not just that it is), improving password habits, and building intuition for what actually makes a password hard to crack versus what merely satisfies an arbitrary complexity rule.
How it works
- Type a password. Checked entirely in your browser as you type — nothing is sent anywhere.
- See the strength meter and score. From very weak to very strong, with the estimated entropy in bits.
- Review specific issues. Concrete reasons the password is weaker than it could be.
Examples
Checking a weak, common password
Input
"password1"
Output
Very weak — matches a commonly leaked password