Password Strength Checker analyses a password's character space and entropy to estimate its strength and resistance to brute-force attacks. It displays entropy in bits, a strength rating, an estimated crack time at 1 billion guesses per second, and a checklist of character diversity requirements.
No. All analysis is done locally in JavaScript. Your password never leaves your device.
Entropy in bits represents the number of binary choices an attacker must make to guess the password by brute force. Each added bit doubles the number of possible passwords.
That figure represents a realistic offline attack using modern GPU hardware against a fast, unsalted hash. Slower hashing algorithms (bcrypt, Argon2) used by well-built services would make real crack times far longer than the estimate shown here — the number is a worst-case reference point, not a universal guarantee.
Usually yes. Length contributes more entropy bits than adding symbol variety to a short password. A 20-character lowercase passphrase can be stronger than an 8-character password with mixed case, numbers, and symbols.
No. This tool only analyzes character composition and length to estimate theoretical entropy — it does not check whether the exact password has appeared in a known data breach. Use a dedicated breach-checking service for that, ideally one that never transmits your actual password.
Many websites still enforce outdated rules (e.g. requiring a symbol but capping length at 12 characters) that don't align with modern entropy-based guidance. This tool measures theoretical entropy, not compliance with any particular site's arbitrary policy.
For most people, yes — a password manager lets you use long, unique, random passwords per site without memorization. This tool is useful for evaluating a specific password's strength, not as a replacement for a password manager's generation and storage.
