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.