What it is
NetCalc Pro is an IPv4 subnet planner. Pick a parent network, split it into smaller subnets, label each one, and ship the plan to whatever format your team uses spreadsheet, Terraform HCL, Markdown, or JSON. A focused toolset sits next to the subnet table: VLSM sizing, supernet calculation, BGP route aggregation, VPC peering overlap checks, workspace diff + comparison, and bulk label editing. Every tool is strictly inside subnet planning; adjacent disciplines (cost, compliance, firewalls, DNS) live in other products.
What it is not
Not an account. You will never log in. Your plan stays on your machine nothing leaves the tab unless you choose to export or share it. Not a live scanner, not a BGP looking glass, not a monitoring tool. Everything is offline-safe after the first load.
Who it is for
Network engineers, cloud architects, DevOps and platform teams, students learning CIDR, and anyone who needs to sketch or document a subnet plan quickly. If you have ever opened a spreadsheet to track /24 allocations by hand, this replaces that spreadsheet.
Sharing your plan
Click Share in the sidebar to copy a link that encodes the entire plan. Paste it into a ticket, a chat, a doc anyone who opens it sees the same tree you do. No sign-up on either end.
Shortcuts
Press ? for the full shortcuts overlay. Press / to jump to the IP search. Escape closes the topmost modal. Ctrl+Z / Ctrl+Y (or Ctrl+Shift+Z) undo and redo every change to the tree.