IPv6 Expand / Compress — full ⇄ shortened
Expand an IPv6 address to its full form or compress it with :: notation, both ways in your browser.
🔒 Runs entirely in your browser. Your input and output are never sent to a server or stored — fully private.
About this tool
This tool expands a shortened IPv6 address to its full eight-group form and compresses a full address back down using :: and leading-zero removal. Paste an address like 2001:db8::1 to see its canonical full form 2001:0db8:0000:0000:0000:0000:0000:0001, or the other way round — useful for firewall rules, documentation and comparing addresses, and it runs entirely in your browser.
Frequently asked questions
What do :: and leading zeros mean in IPv6?
IPv6 lets you drop the leading zeros inside each 16-bit group and replace one run of all-zero groups with a double colon (::). So 2001:0db8:0000:0000:0000:0000:0000:0001 compresses to 2001:db8::1. The :: may appear only once in an address; otherwise it would be ambiguous how many zero groups it stands for.
Why expand an IPv6 address?
The full, fixed-length form makes two addresses easy to compare group by group, and some tools, ACLs or databases expect the canonical representation. Expanding also removes any doubt about how many zero groups a :: was standing in for.
Is my data sent anywhere?
No. Expanding and compressing are text operations performed entirely in your browser, so the addresses you paste are never uploaded or stored on a server.