Password Strength Checker
Check how strong a password is, entirely in your browser.
This is an estimate based on length and character variety, assuming a fast offline attack (about 10 billion guesses per second). It does not check whether a password has appeared in a known breach. Use a long, unique password and a password manager.
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Frequently asked questions
No. The checker runs entirely in your browser using JavaScript. Your password is never uploaded to a server, logged, or stored, so it is safe to test a real password you use.
We estimate entropy as the password length multiplied by log2 of the character-pool size (lowercase, uppercase, digits, and symbols each add to the pool). More length and more character types mean higher entropy and a stronger rating. It is an estimate, not a guarantee.
It is a rough estimate of how long a fast offline attack — around 10 billion guesses per second — would take to find the password by brute force, on average. Real-world attacks vary widely, and a password found in a data breach can be cracked instantly regardless of this figure.
Not on its own. This tool only measures length and character variety; it does not know if your password is a common word, a known breached password, or reused across sites. For real safety, use a long, unique, randomly generated password and a password manager.
Last updated 2026-06-23.