Your files stay on your device
IPv6 ULA Generator and Planner
RFC 4193 unique local addresses plus a /48 planner.
fd + 40 bits from crypto.getRandomValues + subnet ID: the RFC's own algorithm. ULAs are not globally routable by design.
Paste a /48 (or any prefix); children must be longer.
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.