IPv6 Expander and Compressor

IPv6 addresses can be written in a short form using a double colon to stand in for runs of zero groups, or in a full form with all eight groups spelled out. This tool converts between the two so you always have the exact shape you need. Enter any valid IPv6 address and it shows both the fully expanded version, with every group padded to four hex digits, and the shortest compressed version, following the standard rule of collapsing the longest run of zero groups. That is genuinely useful when a config file demands one form but you were handed the other, or when you want to compare two addresses that are written differently but are actually the same. It validates the input and rejects malformed addresses. All processing happens locally in your browser, so the address you enter is never sent to any server.