Free Online IPv4 & IPv6 Subnet Calculator & CIDR Tool

Overview

This application is a professional-grade, browser-based IPv4 and IPv6 subnet calculator designed to provide instant, accurate network address information. It helps IT professionals, students, and system administrators calculate subnets, CIDR ranges, and binary representations without external dependencies.

Core Features

• Dual-Stack Support: Dedicated modes for both IPv4 and IPv6 calculations.
• CIDR Calculator: Input an IP address and prefix length to automatically generate network boundaries.
• Host Information: Clearly displays Network Address, First Usable Host, Last Usable Host, Broadcast Address, and Total Usable Hosts.
• Binary Representation: Real-time conversion of IP addresses and subnet masks into 32-bit (IPv4) or 128-bit (IPv6) binary strings.
• Copy to Clipboard: One-click functionality to copy specific IP addresses for rapid deployment.
• Responsive Design: Optimized for desktop monitors, tablets, and smartphones, ensuring utility on the go.

User Interface Layout

• Header: A clean, minimal title area stating the purpose of the tool.
• Input Section: A high-contrast card featuring a tabbed interface to switch between IPv4 and IPv6. Includes a clean text input field and a slider for adjusting the CIDR prefix range.
• Results Grid: A responsive data table or grid layout that displays network details clearly. Use alternating row colors for improved readability.
• Utility Controls: 'Clear' and 'Reset' buttons clearly visible near the inputs to reset the state instantly.

Design & Aesthetics

• Color Palette: Focused on high-clarity professional tones:
  • Background: #FFFFFF (White)
  • Card Surface: #F9FAFB (Very Light Gray)
  • Primary Accent: #2563EB (Corporate Blue) for primary actions
  • Border/Divider: #E5E7EB (Light Gray)
  • Text: #111827 (Dark Charcoal)
• Visual Style: Modern SaaS aesthetic. Use subtle drop shadows (0 1px 3px rgba(0,0,0,0.1)) on cards to create depth. Utilize rounded corners (border-radius: 8px) for a soft, approachable feel.
• Animations: All interactive elements (buttons, input fields) should feature smooth 200ms transitions for hover states. Results should fade into view when calculated to avoid jarring jumps.

Developer Implementation Guidelines

• Architecture: The app MUST be a single HTML file containing internal CSS and JavaScript. No external build processes.
• Performance: Use Vanilla JS for all calculations. Avoid heavy frameworks.
• Sandbox Safety:
  • DO NOT use localStorage, sessionStorage, or IndexedDB. All state must exist within active JS variables.
  • DO NOT use popups like alert() or confirm(). Use custom modal components built within the HTML if interaction is required.
  • Ensure all external links (if any) use target="_blank" and rel="noopener noreferrer".
• Accessibility: Use proper semantic HTML (main, section, header, label) to ensure screen reader compatibility.