Random IP & MAC Generator
Generate batches of random IPv4, IPv6, or MAC addresses for tests and mocks — public / private / ULA / link-local / UAA / LAA scopes supported.
Uses Math.random() — fine for mock data, not for cryptographic identifiers.
How to use
- Pick an address type and scope.
- Choose how many to generate (up to 500).
- Hit Generate — the bulk-copy button puts the whole list on the clipboard.
About this tool
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Useful when you need plausible-looking but throwaway addresses for unit tests, load generators, firewall-rule worksheets, or sample dashboards. IPv4 excludes loopback, link-local, multicast, broadcast, and the RFC 5737 documentation ranges. IPv6 is generated in 2000::/3 (global), fd00::/8 (ULA), or fe80::/10 (link-local). MAC addresses always set the multicast bit to 0; the locally-administered bit follows the UAA / LAA toggle.
Excluding the documentation ranges is a deliberate choice worth understanding, because for prose the opposite is correct. RFC 5737 reserves 192.0.2.0/24, 198.51.100.0/24 and 203.0.113.0/24 precisely so that examples in books and specifications cannot collide with anything real, and an address written into documentation should come from there. This tool leaves them out because test fixtures often need addresses that look ordinary, and an address that every engineer recognises as an example defeats the purpose of a realistic sample.
That is the trade to make consciously. A random global address belongs to somebody: generate a few thousand for a load generator and some of them route to real hosts, which matters the moment the fixture escapes into anything that opens a connection. Addresses used in tests that make network calls should come from the documentation ranges or from private space, whatever they look like.
The MAC bits are the detail most generators get wrong. The least significant bit of the first octet marks multicast, and setting it produces an address no interface will accept as its own; the next bit marks locally administered, which is what distinguishes an address you made up from one assigned to a manufacturer. A randomly generated address with both bits clear claims an OUI belonging to a real vendor, which is fine in a fixture and wrong on a wire.
The IPv6 prefixes correspond to genuinely different things. 2000::/3 is globally routable, fd00::/8 is the unique local range that is the IPv6 answer to RFC 1918, and fe80::/10 is link-local and never leaves the segment. A test that exercises routing behaviour needs the right one, since they are not interchangeable.
Frequently asked questions
Are the public IPv4 addresses safe to use in screenshots?
Random public IPv4s are likely to be in use — even your screenshot could collide with a real host. For docs prefer the RFC 5737 ranges 192.0.2.0/24, 198.51.100.0/24, or 203.0.113.0/24, which never appear on the public internet.
What does UAA vs LAA mean for MAC?
Universally-administered addresses come from the vendor's OUI registration with IEEE; locally-administered are set by the local admin (VMs, containers, virtualized NICs). The 2nd bit of the first octet distinguishes them.
Which ranges should I actually use in documentation or a screenshot?
The ones reserved for it: 192.0.2.0/24, 198.51.100.0/24 and 203.0.113.0/24 for IPv4, and 2001:db8::/32 for IPv6. They exist precisely so that published examples cannot point at somebody's real host, and any reader who knows them reads the address as an example rather than as a clue. A randomly generated public address belongs to someone.
Is a randomly generated MAC safe to put on a network?
Only if the locally administered bit is set — that is what the LAA option produces, and it marks the address as one an administrator assigned rather than one a manufacturer burned in. A random address with the universal bit set claims a block owned by a real vendor, which can collide with real hardware and confuses anything that looks up the vendor prefix.
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