IPv4 and IPv6 address inspection and subnet math. Inspect an address (version, normalized form, classification: private/loopback/link-local/multicast/global, integer), compute a CIDR block (network, netmask, broadcast, host range, counts), or test whether an address falls inside a range. Deterministic, no lookups. POST a JSON body like: {"cidr":"192.168.1.0/24"}