DevKits

Validation

Match an IPv6 address

Match IPv6 addresses in canonical or compressed form.

Pattern

Regular expression

(?:[A-Fa-f0-9]{1,4}:){7}[A-Fa-f0-9]{1,4}|::1|::

How it works

The pattern above matches full 8-group IPv6 plus common loopback shorthand. Full RFC 4291 conformance (all `::` compression positions) requires a much larger pattern — for real work, use an inet_pton call.

Matches

  • ▸2001:db8::1
  • ▸fe80::1
  • ▸2001:0db8:0000:0000:0000:ff00:0042:8329
  • ▸::1

Non-matches

  • ▸1.2.3.4
  • ▸gggg::
  • ▸12345::

Common gotchas

Matching every valid compressed IPv6 form with regex alone is a well-known nightmare. Use language-native parsing (`net.ParseIP` in Go, `ipaddress` in Python) when correctness matters.

Language snippets

JavaScript

const re = /(?:[A-Fa-f0-9]{1,4}:){7}[A-Fa-f0-9]{1,4}|::1|::/g;

Python

import ipaddress
try: ipaddress.IPv6Address("2001:db8::1")
except ValueError: pass

Go

import "net"
addr := net.ParseIP("2001:db8::1")
if addr != nil && addr.To4() == nil { /* v6 */ }

Java

Pattern.compile("(?:[A-Fa-f0-9]{1,4}:){7}[A-Fa-f0-9]{1,4}|::1|::").matcher(text)

Related patterns

Match an IPv4 address

(?:(?:25[0-5]|2[0-4]\d|1\d{2}|[1-9]?\d)\.){3}(?:25[0-5]|2[0-4]\d|1\d{2}|[1-9]?\d)

Match a MAC address

(?:[0-9A-Fa-f]{2}[:-]){5}[0-9A-Fa-f]{2}

Match an email address

[\w.+-]+@[\w-]+\.[\w.-]+

Match a URL

https?:\/\/[\w.-]+(?:\.[\w.-]+)+[\w\-._~:/?#\[\]@!$&'()*+,;=]*

Match a UUID (v4)

[0-9a-f]{8}-[0-9a-f]{4}-[1-5][0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}

Match a US phone number

(?:\+?1[-. ]?)?\(?[2-9][0-9]{2}\)?[-. ]?[2-9][0-9]{2}[-. ]?[0-9]{4}

Try any pattern live in the Regex Tester →