About this tool
Expand an IPv6 address to its full 8-group form or compress it to the canonical shortest representation following RFC 5952, and derive the first and last address of any prefix along with the total address count.
Compression follows the RFC 5952 rules — longest zero run, leftmost on a tie, never compressing a single zero group — so output matches what routers and RFC-compliant tooling produce. Input must be written as hexadecimal groups: IPv4-embedded forms such as ::ffff:192.0.2.1 and zone identifiers such as fe80::1%eth0 are rejected rather than parsed.