Password Strength Checker
Estimate password entropy and crack time — privately, in your browser.
✓ Entropy + crack-time model · updated June 2026
Your password is never sent anywhere — analysis runs entirely in your browser. Crack time assumes a fast offline attacker (10 billion guesses/sec). Length beats complexity: a long passphrase outperforms a short jumble.
Type a password to see how strong it really is: its entropy in bits, a clear strength rating, and an estimated time to crack it against a fast offline attacker. It flags weak spots like repeated characters and common sequences. Your password is never uploaded — all analysis happens in your browser. Length beats complexity, so a long passphrase wins.
How to use the Password Strength Checker
- Type or paste the password you want to test.
- Read the strength rating, entropy and estimated crack time.
- Lengthen it or add character types to improve the score.
Frequently asked questions
Is my password sent anywhere?
No. The check runs entirely in your browser with JavaScript — your password never leaves your device or touches a server.
What is entropy?
Entropy, measured in bits, estimates how unpredictable a password is. Each extra bit doubles the number of guesses needed; around 60+ bits is considered strong for most accounts.
Why does length matter more than symbols?
Adding length multiplies the search space faster than swapping a letter for a symbol. A long, memorable passphrase usually beats a short complex string.