IPv4 / IPv6 Address Validator & Info

Type 192.168.1.1 into most network tools and you get a ping result or a geolocation row. This tool does something different: it parses the address as bits, names every classification that applies to it, and shows you the reason for each one. The class it falls into, whether it is routable, which RFC governs it, and what each octet looks like in binary and hex. The same logic handles IPv6, expanding compressed notation and detecting link-local, unique-local and IPv4-mapped ranges.

Nothing leaves the browser. The classification runs entirely in the client, which means it works on air-gapped machines and does not log the addresses you test.

Worked Example: 192.168.1.1

The page opens on 192.168.1.1, the default LAN address on most home routers. It is Class C (192.0.0.0 to 223.255.255.255), private (RFC 1918), and not globally routable. The four octets expand to 11000000.10101000.00000001.00000001 in binary, which is how a subnet mask calculation reads the address. The 32-bit integer form is 3232235777, the number a socket library passes to the kernel when you connect to it. The hex form is C0:A8:01:01, which appears in Wireshark packet captures and ARP table entries. Press Load Sample to cycle through 8.8.8.8 (global unicast), 2001:db8::1 (IPv6 documentation), 127.0.0.1 (loopback), and five more.

What Each Field Shows

• Class reports A, B, C, D or E based on the first octet. Class D (224 to 239) is multicast; Class E (240 to 255) is reserved. Classful routing has been superseded by CIDR, but the labels still appear in firewall logs and vendor documentation.
• Scope tells whether the address can appear on the public internet (global), on a single network segment (link-local), only within a private network (private), or never outside the host (loopback).
• Routable confirms an address is not private, not loopback, not link-local, not broadcast and not documentation-reserved, and is therefore globally routable. The tool says so explicitly rather than leaving the reader to infer it from the absence of special flags.
• APIPA flags the 169.254.0.0/16 range, assigned automatically when DHCP fails. It appears on misconfigured hosts and is not routable off the local segment.
• IPv4-mapped IPv6 covers addresses like ::ffff:192.0.2.1 that embed an IPv4 address in the last 32 bits. The tool extracts and labels the embedded address.

Edge Cases Worth Knowing

Leading zeros in an IPv4 octet (010.0.0.1) are rejected with the message “Octet 1 has a leading zero. Use the canonical form without it.” Many parsers silently interpret a leading zero as octal, making 010 equal to decimal 8 rather than 10, a well-known source of firewall rule bugs. Rejecting the ambiguous form outright prevents that class of mistake.

IPv6 accepts both the compressed form (2001:db8::1) and the full 39-character expansion. Bracket notation ([::1]) is stripped before parsing, so addresses copied from a URL or a log line work directly. The double-colon (::) may appear at most once; two of them in one address returns an error naming exactly why.