Password Strength Checker
Type a password to see an instant strength estimate. Nothing you type here ever leaves your browser.
How this checker works
As you type, JavaScript running in your browser measures the password's length, which character types it uses (lowercase, uppercase, numbers, symbols), and estimates its entropy in bits from that character pool. It also flags a handful of well-known weak patterns: common passwords, repeated characters, and simple sequences.
What this tool cannot tell you
It cannot tell you whether the exact password has appeared in a known data breach — doing that safely would require a privacy-preserving lookup against an external database, which this tool does not perform. It also cannot detect every possible weak pattern, such as passwords based on personal information only you would recognize.
Privacy
The password field never submits to a server, is never written to localStorage or cookies, and is not included in any analytics event. Closing or refreshing the page discards it completely.
Frequently asked questions
Does this tool send my password anywhere?
No. The password you type is analyzed entirely in your browser using JavaScript. It is never transmitted over the network, logged, or stored.
Can this tool tell me if my password was in a data breach?
No. Checking against breach databases would require sending information about your password to a third-party service, which this tool intentionally does not do.
What makes the strength estimate accurate or inaccurate?
The estimate assumes your password is close to random within the character types it uses. Passwords built from real words, names or predictable patterns are weaker than the raw entropy number suggests.