Advanced Random Password Generator with Entropy Calculator

Overview

A high-performance, single-file browser utility designed to generate cryptographically secure passwords. The application prioritizes user security and ease of use, featuring real-time entropy calculation to help users understand the strength of their credentials.

Key Features

• Web Crypto API Integration: Uses window.crypto.getRandomValues() for cryptographically secure random number generation.
• Customizable Complexity: Toggle Uppercase, Lowercase, Numbers, and Symbols. Define specific character length (range: 6 to 128).
• Real-Time Entropy Meter: A color-coded strength bar (Weak, Medium, Strong, Excellent) with a numeric entropy score (bits).
• One-Click Copy: Instant clipboard functionality with a brief "Copied!" visual notification.
• In-Memory History: Displays a list of the last 10 generated passwords, held strictly in volatile memory (erased on reload).
• Responsive Design: Optimized for mobile, tablet, and desktop viewing.

UI & Layout Specification

• Header: Clean, professional title area with a minimal navigation concept.
• Main Tool Area: A centered, card-based interface with a large, selectable display area for the password.
• Controls: A clean grid of toggles for character types and a slider for length adjustment.
• Visual Feedback: The entropy meter sits directly beneath the password display, providing instant color-coded feedback (Red = Low, Yellow = Medium, Green = Strong).
• Aesthetic:
  • Color Palette: Off-white backgrounds (#f9fafb), slate gray text for legibility (#1f2937), and a vibrant accent blue (#2563eb) for primary buttons. Success green (#059669) for entropy strength.
  • Typography: Clean, sans-serif fonts (e.g., system-ui, sans-serif) for high readability.
  • Animations: Soft fades for state changes, hover-lift effects on buttons, and smooth transition animations for the entropy progress bar.

Developer Directives & Technical Constraints

• Single-File Requirement: All HTML, CSS, and JavaScript must reside within one single .html file. No external frameworks or backend dependencies.
• Zero-Storage Policy: Strictly forbidden from using localStorage, sessionStorage, IndexedDB, or cookies. Maintain state using standard JavaScript variables within the app context.
• Sandboxed Compatibility: The app must function in a null-origin iframe environment. Avoid any alert(), confirm(), or prompt() calls; implement custom modal UIs if necessary.
• Performance: Minimize DOM manipulation overhead to ensure instantaneous response times during password generation.
• External Links: All links to external resources (if any) must include target="_blank" and rel="noopener noreferrer".
• No Dark Mode: Maintain a vibrant, professional light-mode aesthetic throughout the implementation.