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IPv4 Free Space Finder
Given a parent IPv4 network and its existing allocations, list the unallocated CIDR blocks and the utilization.
This tool handles input and primary processing in your browser and is designed not to send the input to QuickKit’s server.
How it works
Enter the parent block and one allocation per line (bare addresses count as /32). The free list is the parent minus the union of all allocations, as a minimal CIDR set. Allocations that are not fully inside the parent are listed under "outside parent" and only their in-parent portion counts toward utilization. Up to 5,000 allocations.