What counts as a private IPv4 address?

RFC 1918 reserves three private ranges: 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16. Addresses in these blocks are not routable on the public internet and are safe to use freely in test data without affecting any real host.

How does CIDR-constrained generation work?

Enter a block such as 192.168.1.0/24. The tool keeps the network bits fixed and randomises only the host bits, so every generated address falls inside that subnet. A /24 yields 256 addresses, a /16 yields 65,536, and so on.

Will public IPv4 addresses hit real machines?

Possibly. Public mode generates globally routable addresses while skipping reserved and private ranges, so an address could belong to a real host. Use private mode for test data you never want to accidentally contact.

How are IPv6 addresses formatted?

IPv6 addresses are eight 16-bit groups in hexadecimal. The tool generates random groups and applies the standard compression rule, collapsing the longest run of zero groups to a double colon, producing the canonical shortened form.

Does this contact any server?

No. Addresses are computed locally in JavaScript, so nothing is sent anywhere and the tool works fully offline.

IP Address Generator

This generator produces random IPv4 and IPv6 addresses for network testing. You can keep output inside the RFC 1918 private ranges, generate globally routable public addresses, or constrain everything to a specific CIDR subnet so the addresses are valid for the network you are modelling.

How it works

For IPv4 each address is four octets. Private mode draws from one of the RFC 1918 blocks; public mode picks globally routable octets while skipping reserved ranges; CIDR mode fixes the network prefix and randomises only the host bits:

private  : 10.x.x.x  |  172.16-31.x.x  |  192.168.x.x
loopback : 127.x.x.x
cidr     : keep top /n bits, randomise the rest

For IPv6 the tool generates eight random 16-bit groups, then applies the canonical compression rule — the longest run of consecutive all-zero groups is replaced by :: and leading zeros within each group are dropped — to produce the standard shortened form.

Tips and notes

Use private mode for any test data you never want to accidentally route to a real host, and public mode only when you specifically need globally routable values. CIDR mode is ideal for seeding addresses inside a lab subnet, firewall rule, or DHCP scope. For IPv6, remember that :: may appear at most once in an address — the generator respects that, so the output is always valid and parseable.