Password Entropy Checker
Analyse password strength, estimate crack time, and generate cryptographically secure passwords
Check how strong a password is by its entropy and estimated time to crack, or generate a random password or passphrase with your chosen length and character sets using the browser's cryptographic random number generator. More free security tools.
| Attack Scenario | Speed | Estimated Time |
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Password strength isn't about length rules or forced character classes — it's about entropy, the number of bits of randomness an attacker has to search through. This tool estimates entropy from the character sets actually used and the length, then converts that into an approximate offline crack time, so you can see why "P@ssw0rd1!" is weak despite satisfying most complexity policies, while a longer random passphrase is not.
The generator side uses the browser's Web Crypto API (crypto.getRandomValues), a cryptographically secure pseudo-random number generator, rather than Math.random() — which is predictable and unsuitable for anything security-sensitive. Everything runs locally in your browser; no password you type or generate is transmitted anywhere.
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