IPv6 Address Tool

📖 Tool Introduction

An IPv6 address spans 128 bits and is written in eight groups of four hexadecimal digits separated by colons. To keep addresses readable, the standard allows replacing the longest run of consecutive zero groups with the shorthand ::. That compression is convenient for humans, but it makes programmatic parsing, log comparison and configuration review error-prone: 2001:0db8:0000:0000:0000:0000:0000:0001 and 2001:db8::1 describe exactly the same host, yet at a glance it is surprisingly hard to be sure. The IPv6 Address Tool exists to remove that doubt: you type an address in any accepted form, including the /prefix suffix, the %interface zone suffix, and the embedded IPv4 notation ::ffff:192.168.1.1. The tool first validates the input strictly and then presents two canonical views: the expanded view restores the :: into the correct number of zero groups and pads each group to four hex digits, while the compressed view drops leading zeros and replaces the longest zero run with :: exactly as RFC 5952 recommends. Alongside the two views, it classifies the address for you, telling whether it is a global unicast address, a link-local address, a unique-local address, a multicast address, an IPv4-mapped address, or one of the documentation ranges reserved for examples. The UI uses a large monospace display with type badges, and the eight 16-bit groups are shown side by side as tiles with zero groups dimmed, so you can verify each group by eye. Everything runs locally in the browser, which means you can paste internal addresses and they never leave your machine.

✨ Key Features

• Strict validation: checks that :: appears at most once, that group counts are correct, and that each group holds one to four hex digits
• Zero-compression restoration: expands :: into the right number of zero groups, producing the full eight-group form
• RFC 5952 compression: strips leading zeros and collapses the longest zero run into :: for the canonical recommended form
• Embedded IPv4 support: correctly handles IPv4-mapped and compatible addresses such as ::ffff:192.168.1.1
• Type detection: labels global unicast, link-local, unique-local, multicast and documentation ranges automatically
• Per-group visualisation: the eight 16-bit groups are tiled side by side with zero groups dimmed for manual cross-checking

📝 How to Use

1. Type the IPv6 address you have on hand, for example 2001:db8::1
2. You may also type a prefixed form such as 2001:db8::/32 or an embedded IPv4 form such as ::ffff:192.168.1.1
3. Click the Parse button; malformed input triggers a friendly message instead of a crash
4. Switch between the Expanded and Compressed tabs to see the two canonical notations
5. Click Copy result to grab both forms together on the clipboard

⚠️ Notes

• Single :: only: a valid address contains at most one ::, and a second occurrence makes the input illegal
• Group counts: without :: you need exactly eight groups; with :: the remaining groups must not exceed seven
• Lowercase output: the compressed view always prints lowercase hex digits, following the RFC 5952 recommendation
• Embedded IPv4: ::ffff:a.b.c.d is recognised as an IPv4-mapped address, with the last 32 bits held by the IPv4 address
• Parse only: this tool does no subnetting or reverse DNS lookup; all computation happens locally