Password Generator

Secure password generator with entropy analysis and crack-time estimation. Everything runs client-side -- no data is sent to any server.

Live Demo

Features

• Cryptographic randomness -- uses crypto.getRandomValues() for true randomness
• Entropy calculation -- Shannon entropy in bits based on character pool
• Crack-time estimation -- time to brute-force at 4 billion guesses/second (GPU baseline)
• Strength meter -- 5-level visual indicator (Very Weak to Very Strong)
• Configurable charsets -- numbers, lowercase, uppercase, symbols (toggle independently)
• Length control -- 4 to 128 characters with slider and +/- buttons
• Guaranteed charset inclusion -- at least one character from each selected type
• Dark / Light mode -- toggle or auto-detect from system preference
• i18n -- English and Portuguese (auto-detect from browser language)
• Copy to clipboard -- one-click copy with visual feedback
• Zero dependencies on backend -- pure client-side, works offline

Tech Stack

• React 19
• TypeScript
• Tailwind CSS v4
• Vite
• Lucide icons

Getting Started

git clone https://github.com/gmowses/password-generator.git
cd password-generator
npm install
npm run dev

Open http://localhost:5173 in your browser.

Build

npm run build

Static files are generated in dist/.

How It Works

Entropy

Entropy is calculated as log2(pool_size ^ password_length), where pool_size is the total number of possible characters based on selected charsets:

Charset	Pool Size
Numbers (0-9)	10
Lowercase (a-z)	26
Uppercase (A-Z)	26
Symbols	30

Crack Time

Estimated time to brute-force the password assuming:

• Offline attack with modern GPUs
• 4 billion guesses per second
• No password reuse or pattern detection

Strength Levels

Entropy	Level
< 28 bits	Very Weak
28-35 bits	Weak
36-59 bits	Fair
60-127 bits	Strong
128+ bits	Very Strong

License

MIT -- Gabriel Mowses