Password Strength Checker
The problem: Weak passwords are the leading cause of account breaches, yet most password-strength indicators only show a single color bar with no actionable feedback.
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100% In-Browser Execution. Zero server uploads. Your data never leaves this tab — disconnect your internet and the tool keeps working.
Password Strength Checker: the complete guide
A password strength checker analyzes a password against established security criteria — length, character variety, common patterns, and entropy — and translates these technical metrics into actionable feedback: a strength score, estimated crack time at GPU-speed brute force, a detailed criteria checklist, and specific improvement suggestions. This tool also includes a cryptographically-random password generator that produces passwords meeting all recommended security thresholds, with a configurable length slider from 8 to 64 characters.
Password entropy and what it means
Entropy measures how many bits of randomness a password contains. It is calculated as log₂(pool_size^length), where pool_size is the number of unique characters the password draws from (26 lowercase + 26 uppercase + 10 digits + 32 special characters = 94 maximum). A password with 60+ bits of entropy is considered strong against offline brute-force attacks. The crack time displayed assumes a modern GPU performing 10 billion guesses per second — the realistic speed of a dedicated cracking rig using Hashcat against a leaked MD5 hash database.
What makes a password genuinely secure
Length is the single most impactful factor. A random 16-character lowercase-only password (entropy ~75 bits) is stronger than a complex 8-character password with symbols (entropy ~52 bits). Adding character class diversity (uppercase, numbers, symbols) increases the pool size and therefore entropy, but only marginally compared to adding length. The most dangerous patterns are: common passwords (password123), keyboard walks (qwerty), repeated characters (aaaaaa), and dictionary words regardless of simple substitutions (p@ssw0rd).
Step by step: how to use Password Strength
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Type your password in the input field — analysis updates in real time.
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Click the eye icon to toggle password visibility.
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Review the strength score (0-100), entropy and estimated crack time.
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Check the criteria list to see exactly which requirements are met and which are not.
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Read the Suggestions section for specific, actionable improvements.
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Use the password generator at the bottom to create a strong random password of your chosen length.
Security & privacy
Password analysis and generation happen entirely in your browser tab. Your password is never transmitted to any server, logged, stored or shared. The analysis runs on the local JavaScript engine using only the characters you type. The generated passwords use Math.random() shuffled with the Fisher-Yates algorithm — suitable for account passwords, but not for cryptographic key material where crypto.getRandomValues() should be used.