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IPv6 ULA Generator

Generate RFC 4193 Unique Local IPv6 Addresses with a random 40-bit Global ID. Perfect for private networks and lab environments.

Subnet ID (0000–FFFF)

Frequently Asked Questions

A Unique Local Address (ULA) is an IPv6 address in the fd00::/8 block, defined in RFC 4193. ULAs are similar to IPv4 private addresses (10.x, 192.168.x) — they're routable within your network but not on the public internet.

The 40-bit Global ID is generated using cryptographically secure random bytes (crypto.getRandomValues). RFC 4193 recommends using a hash of timestamp and EUI-64, but random generation is widely accepted and avoids needing a system MAC address.

Yes — enter a 16-bit subnet ID (0–FFFF) to organize your network. The default is 0000. Combined with the random Global ID, this gives you a unique /64 prefix for each subnet.