SubNet Calc for Android by Libor Benes

SubNet Calc for Android:
• a lightweight, privacy-focused tool for network planning, troubleshooting, and education, optimized for Android devices and compatible with Firefox desktop.
• designed for network engineers, sysadmins, network analysts, and students.
• effortlessly calculates IPv4 (not IPv6) subnets in a compact, touch-friendly popup.

Enter an IPv4 address, a CIDR mask, and the desired number of subnets to instantly generate a scrollable table with detailed subnet information, including network addresses, broadcast addresses, host ranges, and usable hosts.

Copy results as CSV text for seamless pasting into Google Sheets, Excel, Android’s Documents app, text messaging apps, or network documentation. CSV output ensures reliable alignment across spreadsheet and text applications.

Key Features:
• IPv4 Subnet Calculation: Computes accurate subnet details for any valid IPv4 address, CIDR (0–32), and number of subnets, powered by ipaddr.js.
• Touch-Friendly Interface: Optimized for Android with smooth touch scrolling for wide or tall tables, best viewed in horizontal screen orientation for optimal table visibility (vertical screens may feel cramped but are functional). Touch dragging enables easy navigation. Note: Horizontal scrollbar may not appear (not needed due to touch scrolling); vertical scrollbar is small but functional.
• CSV Output: Copies results as CSV for compatibility with Google Sheets, Excel, and Android apps.
• Error Handling: Clear error messages for invalid inputs (e.g., 256.168.0.0, /33).

Security & Privacy:
• No Permissions: Requires no browser permissions, ensuring minimal access.
• Offline Operation: Performs all calculations locally, collecting no user data for maximum privacy.
• Safe Coding: Uses secure DOM manipulation (createElement, textContent) to prevent XSS risks.
• Manifest v2 Compliance: Adheres to Mozilla’s standards for Firefox add-ons.
• Minimal Design: Compact popup (~300–360px wide on Android) with a clean, teal-themed interface.

SubNet Calc for Android relies on ipaddr.js, a lightweight, MIT-licensed JavaScript library (version 2.2.0, 13 KB, sourced from https://github.com/whitequark/ipaddr.js) included in the add-on’s local codebase. No network connections are needed, ensuring reliable and secure IPv4 address parsing and validation.