ipaddress-go

February 26, 2026 ยท View on GitHub

Go library for handling IP addresses and subnets, both IPv4 and IPv6

IP address and network manipulations, CIDR, address and subnet operations, address ranges, iterators, containment checks, longest prefix match, subnetting, address tries, address collections, and more, with polymorphic code

Docs Site

Godoc Go Reference

Code Examples

List of Users

VersionNotes
1.2.1Requires Go 1.12 or higher
1.4.1Requires Go 1.13 or higher
1.7.1Requires Go 1.18 or higher

In your go.mod file:
require github.com/seancfoley/ipaddress-go v1.7.1

In your source file:
import "github.com/seancfoley/ipaddress-go/ipaddr"

Packaged as a Linux Fedora rpm and as a Linux Debian, available from Ubuntu

Also available as a Java library from the IPAddress repository

Getting Started

starting with address or subnet strings

import "github.com/seancfoley/ipaddress-go/ipaddr"

ipv6AddrStr := ipaddr.NewIPAddressString("a:b:c:d::a:b/64")
if ipAddr, err := ipv6AddrStr.ToAddress(); err != nil {
	// err.Error() has validation error
} else {
	// use the address
}

...or avoid errors, checking for nil:

str := ipaddr.NewIPAddressString("a:b:c:d:e-f:f:1.2-3.3.4/64")
addr := str.GetAddress()
if addr != nil {
	// use address
}

starting with host name strings

hostStr := "[::1]"

host := ipaddr.NewHostName(hostStr)
err := host.Validate()
if err == nil {
	if host.IsAddress() {
		fmt.Println("address: " + host.AsAddress().String())
	} else {
		fmt.Println("host name: " + host.String())
	}
	// use host
} else {
	fmt.Println(err.Error())
}