Password Strength Tester
Check how strong a password is. This tester estimates its entropy, flags common weaknesses, and shows roughly how long it would take to crack — all in your browser.
About this tool
A password strength tester estimates how resistant a password is to guessing and brute-force attacks. It looks at length, the variety of character types, and common weaknesses (dictionary words, repeats, keyboard runs and predictable patterns), then converts that into an entropy estimate and an approximate crack time.
Tested privately
Your password is analysed entirely in your browser. It is never sent to a server, logged, or stored — type with confidence.
How the estimate works
The tester calculates the size of the character set you used and multiplies by length to get a baseline entropy in bits, then applies penalties for patterns a real attacker would try first — common passwords, repeated characters, sequences like "1234" or "abcd", and simple keyboard walks. The crack-time figure assumes a fast offline attacker making billions of guesses per second, which is the realistic worst case if a site's password database leaks.
Reading the result
Treat the rating as guidance, not a guarantee. "Strong" means resistant to brute force, but a password that is long yet based on a famous quote can still be weak against smart attacks. The most reliable path to strength is a long, random password or passphrase from a generator.
Frequently asked questions
Yes. The analysis runs entirely in your browser with JavaScript — your password is never transmitted, logged or stored. That said, for an account you actively use, testing a similar pattern rather than the exact password is good general hygiene.
It assumes a determined offline attacker who has stolen a password database and can make billions of guesses per second against the hash. The estimate is based on the password's entropy — the real time varies with the attacker's hardware and the hashing used.
Length helps, but predictable content hurts. Dictionary words, names, dates, repeated characters and keyboard patterns are tried first by cracking tools, so they lower the effective strength regardless of length.
Use a generator to create a long, random password or a multi-word passphrase, and store it in a password manager. Random beats clever every time.