SubnetPlanner

Fully featured IPv4/IPv6 subnetting and IP planning web app. Static HTML/CSS/JS — no server-side code, no build tools, no dependencies.

Features

• IPv4 Subnet Calculator — network address, broadcast, subnet mask, wildcard mask, first/last usable host, total usable hosts, IP range
• IPv6 Subnet Calculator — compressed/expanded forms, first/last address, total addresses (128-bit BigInt math)
• VLSM Subnet Splitter — split blocks into smaller subnets with alignment, remaining space breakdown, visual tree hierarchy
• IP Plan Builder — sites, VLANs, prefixes, and individual IP address assignments with collapsible tree UI
• NetBox CSV Export — prefixes and IP addresses in NetBox import format
• PDF Report Export — professional IP plan document with site summaries, prefix tables, and IP address tables
• localStorage Persistence — IP plan saves automatically between sessions
• Dark Mode UI — professional, responsive layout

Deploy

Option 1: Any Web Server

Copy the SubnetPlanner/ folder to your web server's document root. No build step required.

https://yourdomain.com/tools/subnetplanner/index.html

Option 2: Open Locally

Open index.html directly in any modern browser. All features work offline except PDF export (requires jsPDF from CDN on first load).

Option 3: SharePoint

See SubnetPlanner-SPFx for the SharePoint Framework web part version.

File Structure

SubnetPlanner/
  index.html              Main page with 4 tabs
  css/
    style.css             Dark mode professional styling
  js/
    calculator.js         IPv4/IPv6 calculator logic
    subnetSplitter.js     VLSM splitting logic
    ipPlan.js             IP plan builder (sites, VLANs, prefixes, IPs)
    export.js             NetBox CSV + PDF export
    data.js               localStorage persistence

NetBox CSV Export Format

Prefixes CSV:

prefix,site,vlan_id,status,description
10.0.0.0/24,OVH Montreal,1,active,Internal VM network

IP Addresses CSV:

address,device,interface,status,description
10.0.0.1,GC02-Router,LAN,active,Gateway

Import directly into NetBox via the CSV import tool.

Technical Details

Framework	Vanilla JavaScript (no frameworks)
Dependencies	jsPDF + jspdf-autotable (loaded from CDN)
Browser Support	Any modern browser with BigInt support (Chrome, Firefox, Edge, Safari)
Data Storage	localStorage (persists between sessions)

Related

• SubnetPlanner-SPFx — SharePoint Framework web part version
• NetBox — IPAM/DCIM tool (CSV export format matches NetBox import)