IPv6 Shortener

The shortener compresses a full IPv6 address to its shortest form and expands a short one back. Along the way it shows everything the address reveals: its type, the reverse DNS record, binary and decimal notation, and the network range for a prefix.

RFC 5952 sets the rules. Leading zeros in each group are dropped, letters are written in lowercase, and "::" replaces the longest run of zero groups.

For addresses with IPv4 inside, like ::ffff:192.0.2.1, the standard recommends keeping the IPv4 part at the end. The tool shows that form and a pure hexadecimal one, since different systems write it differently.

The address type comes from the IANA registry of special-purpose blocks: link-local, unique local, documentation, NAT64, 6to4, Teredo, and others. For NAT64, 6to4, and Teredo the tool extracts the IPv4 address hidden inside.

Add a prefix, /64 for example, and you get the network, the first and last address, and the total number of addresses in it. The list field parses many addresses at once and exports the results to CSV.