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Generate private IPv6 ULA prefixes per RFC 4193. Use for lab networks; for subnet math use ipv6-calculator. Input: optional seed. Returns ULA prefix. 100% client-side.
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Generates random IPv6 Unique Local Addresses (ULA) in the fd00::/8 range. Displays each address with its /64 prefix, full expanded form, and compressed notation. Supports batch generation of up to 50 addresses with individual and bulk copy.
IPv6 ULAs serve the same purpose as RFC 1918 private IPv4 addresses — they provide non-routable addresses for internal networks, lab environments, and service mesh configurations. Generating them manually is tedious and error-prone.
This tool is part of the DevStackIO platform — a collection of free online developer tools from DevStackIO. Browse more free developer resources on DevStackIO.
Network engineers designing dual-stack or IPv6-only networks, DevOps engineers configuring Kubernetes pod networking, homelab enthusiasts setting up IPv6, and students learning IPv6 addressing.
Enter the number of ULA addresses to generate (1-50)
Press Generate to create the addresses
View the compressed form (with /64 prefix) for configuration files
View the full expanded form for learning or debugging
Click any address or field to copy it to your clipboard
Input: Count 1 — Output: fd3a:7c42:910b::/64 (compressed), fd3a:7c42:910b:0000:0000:0000:0000:0000 (expanded)Input: Count 3 — Output: 3 unique fd00::/8 ULAs, each with random 40-bit Global IDsWhat is an IPv6 ULA?
A Unique Local Address is the IPv6 equivalent of a private IPv4 address (like 192.168.x.x). It is not routable on the public internet.
Why fd00::/8 and not fc00::/8?
The fc00::/8 block was originally split into fc00::/8 (locally assigned) and fd00::/8 (random). Only fd00::/8 is in common use today.
Can two organizations have the same ULA?
Statistically extremely unlikely (40-bit random ID = ~1 trillion possibilities), but for critical infrastructure, consider registering with a coordination authority.
Authoritative specifications, standards, and in-depth reading for IPv6 ULA Generator.
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