Password Strength Checker
Check the strength of a password with entropy calculation, common-password check and improvement tips. Runs in your browser — no data is sent.
- At least 8 characters
- At least 12 characters
- Lowercase letter
- Uppercase letter
- Number
- Special character
- Not a common password
- No sequences (123, abc)
- No repetitions (aaa)
How is password strength measured?
Strength comes from an entropy estimate, in bits: a larger character set and a longer password push up the number of combinations an attacker would have to try. The math is log₂(charset size) × length.
On top of that, we look at practical criteria. Minimum length matters, along with a mix of upper and lowercase, the presence of digits and symbols, and no predictable sequences (1234, abcd) or repetitions (aaaa). If a password shows up in known leak lists, it gets flagged as insecure no matter how high the entropy is.
The whole evaluation runs in your browser. Nothing is sent to servers or stored.
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Check a password's strength
A truly secure password doesn't have to look complicated. What counts is being hard to guess. This checker gauges strength by calculating entropy, which is the measure of unpredictability, and also checks whether the password shows up among the most common and already-leaked ones.
It goes beyond the verdict. You also get concrete tips to improve: increase the length, vary the character types, steer clear of obvious words. Pairing the analysis with the guidance helps you understand why a password is weak and what to do to make it more robust.
The whole assessment runs in the browser, the password never leaves your device, and nothing is logged. Even so, just to be safe, avoid testing here the actual password you use on critical accounts.