Password Strength Analyzer

Overview

Scores a password from Very Weak to Excellent as you type, entirely in the page, with a character-class entropy estimate, a crack-time projection at ten billion guesses per second, and specific suggestions - mix case, add digits, avoid repeats - tied to what the input is actually missing. Nothing is uploaded and no breach database is consulted.

How It Works

Type into the password box and the analysis updates on every keystroke: a color-coded strength bar, the label, estimated entropy in bits, the character space in use, and a crack-time estimate. A suggestions panel lists concrete fixes - minimum length, mixed case, digits, special characters, fewer repeats. The tool zeroes the score outright when the input starts with an extremely common pattern such as password, qwerty, 123, abc or letmein.

Step-by-Step Usage Guide

1. Type or paste a candidate password and watch the bar, label, entropy and crack time update live.
2. Read the suggestions panel: each item corresponds to a scoring rule your input currently fails.
3. Iterate - lengthen, mix character classes, break up repeats - until the label and entropy reach your target.
4. Compare two candidates in sequence and note how much entropy each added character class contributes.

Technical Specifications & Standards

The score is an additive heuristic, and knowing its terms tells you what it can and cannot see. It awards one point each for eight, twelve and sixteen characters, one for mixing cases, one for a digit and one for a symbol, and subtracts one for any character repeated three or more times in a row. Entropy is the textbook upper bound: length times log2 of the character space, counting 26 for lowercase, 26 for uppercase, 10 for digits and 33 for symbols. Crack time divides 2^entropy by an assumed ten billion guesses per second and renders in seconds through millennia. That model assumes every character is independently random - it cannot detect that Password1! is a dictionary word with decorations, and it has no breach-corpus check like Have I Been Pwned, so a password leaked in a real breach can still score well. The common-prefix rule compensates only for the most obvious cases. Treat the output as a floor estimate of strength against a fast offline attacker, and pair it with a breach lookup when the stakes are real. One more honesty point: the input field is plain text, so what you type is visible on screen and in page memory - analyze a similar password if yours is in active use.

Targeted Use Cases

• Screening new passwords during signup-flow testing, before wiring a real policy validator.
• Demonstrating to a team why length dominates: watch entropy climb by roughly 4.7 bits per added lowercase character.
• Checking that your UI's own strength meter agrees with an independent estimate before you ship it.
• Teaching how entropy estimates work, including their blind spots around dictionary words and real-world leaks.

Notes & Gotchas

• Prioritize length over symbol soup. A twenty-character passphrase from random words beats a short string crammed with special characters.
• Do not rely on a good score alone. The tool cannot see breach databases - check Have I Been Pwned or similar for real-world exposure.
• Avoid patterns the heuristic cannot model, like a single dictionary word with appended digits, even when the score looks acceptable.
• Analyze a stand-in password if the real one is in use. The field is plain text and the value sits in page memory as you type.

Frequently Asked Questions