Password Strength Checker
Test any password for strength, entropy, and estimated crack time. The tool evaluates password length, character variety, common patterns, keyboard walks, sequential characters, repeated characters, and matches against common password lists. Crack time estimates cover three attack scenarios: online throttled (100 guesses per second), online unthrottled (10,000 guesses per second), and offline GPU cracking (100 billion guesses per second). All analysis runs entirely in your browser \u2014 your password is never sent to any server, never stored, and never logged.
Why Password Strength Matters
Weak passwords are responsible for over 80% of data breaches. Common words, personal information, and predictable patterns (like "Password123!" or "Summer2024") can be cracked in seconds by modern GPU clusters. A strong password uses length, character variety, and avoids dictionary words and patterns. Each additional character multiplies crack time \u2014 a 16-character password with mixed types takes centuries to crack, while an 8-character one can fall in minutes.
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Deep Dive: The Complete Password Strength Guide
Entropy math, the five score tiers, three attacker models, pattern penalties, length versus complexity, master-password strategies, and the workflow for using the checker without ever typing your real password.
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Frequently Asked Questions
Is it safe to type my real password here?+
Yes. All password analysis happens entirely in your browser via JavaScript. Your password is never transmitted to any server. You can verify this by opening your browser's Network tab (F12) \u2014 you'll see zero requests while typing. For maximum paranoia, you can disconnect your internet and the tool still works. That said, a reasonable security practice is to test passwords similar to your real ones rather than the exact password you use.
What is password entropy?+
Entropy measures unpredictability in bits. Each bit doubles the possible passwords an attacker must try. 60+ bits is considered strong; 80+ bits is excellent. A 12-character password using mixed case, numbers, and symbols has roughly 77 bits of entropy. The tool reduces reported entropy when it detects patterns that make guessing easier (common words, keyboard walks, years, etc.).
What makes a strong password?+
Length beats complexity. A 16-character passphrase like "correct-horse-battery-staple" is stronger than an 8-character password with symbols ("P@ssw0rd!"). Aim for 12+ characters, avoid dictionary words when possible, and never reuse passwords across accounts. Better yet: use a password manager to generate and store unique passwords for every account.
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