Subnet Planner

Hierarchy — click a prefix for details, use Split / Join to shape the plan

Import CSV

Paste a CSV exported from this tool, or any CSV with a prefix column (and optionally label). Each prefix is placed inside the smallest listed prefix that contains it; anything not covered by another becomes a base of its own, so a plan with several bases comes back intact. Labels on groups and leaves are both restored. This replaces the current plan.