IPv6 ULA Generator
Generate a random IPv6 Unique Local Address (RFC 4193) for use on a private network, similar in purpose to IPv4's private address ranges.
Recommended Settings
Pro Tips
- •Unique Local Addresses always start with the fd00::/8 prefix, reserved specifically for private, non-internet-routable IPv6 addressing
- •The 40-bit Global ID is randomly generated so that two independently generated ULA prefixes are extremely unlikely to collide, even without central coordination
- •Unlike IPv4's small private ranges, a single ULA /48 prefix gives you 65,536 possible /64 subnets - more than enough for any home or organization network
- •Generate this once and reuse the same prefix across your network - regenerating for every device would defeat the purpose of a stable private addressing scheme
Most Popular
Most people generate one ULA prefix to use consistently across their entire home lab or private network
When to Use This Tool
Get a randomly generated, collision-resistant prefix for a private IPv6 network.
Generate a stable IPv6 addressing scheme for a home lab or container network.
See how a Unique Local Address is structured and randomly generated.
Get an IPv6 equivalent to IPv4's 192.168.x.x or 10.x.x.x private ranges.
How It Works
Generate random bytes combined with the current timestamp as input entropy, following the method described in RFC 4193
Hash that combined input with SHA-1 and take the low-order 40 bits as the Global ID
Prefix the Global ID with fd (marking it as a locally-assigned ULA) and append a randomly chosen 16-bit subnet ID to form the final /64 prefix
100% Private
Files never leave your device. All processing happens locally in your browser.
Lightning Fast
Powered by Client-side Web Crypto API (SHA-1, getRandomValues) per RFC 4193 for optimal performance on modern browsers.
Open Source
Built with verified, open-source libraries. Fully transparent.
Frequently Asked Questions
What's the IPv6 equivalent of IPv4's 192.168.x.x?
Unique Local Addresses (fd00::/8) serve the same purpose as IPv4's private ranges - they're for use within a private network and aren't routable on the public internet.
Will my generated prefix collide with someone else's?
It's extremely unlikely - the 40-bit Global ID gives over a trillion possible values, and RFC 4193's pseudo-random generation method is specifically designed to minimize collisions even without central registration.
Should I generate a new ULA for every device?
No, generate one prefix for your entire network and then assign individual addresses or subnets within it - regenerating per device would create an unmanageable, disconnected address space.
Is this address routable on the internet?
No, like IPv4 private addresses, ULAs are meant for private, internal network use only and won't be routed across the public internet.