Local IPv6 (ULA) Generator

Generate a unique local IPv6 address for a private network. The tool builds a random fd00::/8 prefix with a 40-bit global ID per RFC 4193, gives you a ready-to-use /48 and a sample /64 subnet, and lets you regenerate as many as you like. Created in your browser.

Read the guide: What Is a Unique Local IPv6 Address
Unique local address (RFC 4193)
Your ULA prefix (/48)
fd39:bbd6:23d8::/48
A random fd00::/8 prefix with a 40-bit global ID, generated in your browser.
/48 prefixfd39:bbd6:23d8::/48
40-bit global ID39bbd623d8
Sample /64 subnetfd39:bbd6:23d8::/64

The /48 is yours to keep for a private network. Carve it into /64 subnets by setting the 16 bits after the prefix, giving you 65,536 subnets, each with room for billions of hosts.

How it works

  1. 1

    Read your prefix

    The page generates a random fd00::/8 /48 prefix the moment it loads.

  2. 2

    Regenerate if you want

    Press Regenerate to roll a fresh random global ID and prefix.

  3. 3

    Use the /48

    Copy the /48 for your network and carve it into /64 subnets, one shown as an example.

Instant & 100% private — nothing is uploaded

Everything runs locally in your browser. Your code, text and files are processed on your own device and are never sent to a server — so there are no upload waits, no size limits from us, and nothing is ever stored or logged.

Frequently asked questions

What is a unique local address?
A unique local address (ULA) is a private IPv6 range, defined in RFC 4193, that is not routed on the public internet. It is the IPv6 counterpart to private IPv4 ranges like 192.168.0.0/16. Every ULA starts with fd, followed by a random 40-bit global ID, which makes accidental clashes between networks extremely unlikely.
Why is the global ID random?
RFC 4193 asks you to pick the 40-bit global ID at random so that two separate networks almost never choose the same prefix. That keeps your range stable and lets you merge or link networks later without renumbering. The tool draws the random bits from your browser cryptographic random source.
How do I split the /48 into subnets?
The 16 bits right after the /48 prefix are the subnet ID, giving you 65,536 /64 subnets. Set those bits to 0000 for your first subnet, 0001 for the next, and so on. Each /64 has room for a vast number of hosts, which is the standard subnet size in IPv6.
Is the address generated privately?
Yes. The prefix is created entirely in your browser and is never sent anywhere, so you can generate ranges for internal networks safely and even offline.

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