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IPv6 ULA Generator and Planner

RFC 4193 unique local addresses plus a /48 planner.
Clear

fd + 40 bits from crypto.getRandomValues + subnet ID: the RFC's own algorithm. ULAs are not globally routable by design.
ULA base prefix

Paste a /48 (or any prefix); children must be longer.
/56 sites/64 subnets

Generate or paste a ULA base, then list its /56 sites or /64 subnets with first/last/count.
Nothing in yet

Paste, drop, or type to begin. Everything stays on this device.

Next door in Network

- IPv6 prefix calculator (/network/ipv6-subnet)
- IPv6 expand & compress (/network/ipv6-format)
All network tools (/network)

Canonical HTML: https://nutter.tools/network/ula
Markdown version: https://nutter.tools/network/ula/index.md
Plain-text version: https://nutter.tools/network/ula/index.txt
Agent index: https://nutter.tools/llms.txt