Generates random 48-bit MAC addresses in various formats. The locally administered bit (bit 1 of the first octet) is set to avoid conflicts with real manufacturer addresses. Useful for testing, network simulation, and dummy data. Runs entirely in your browser.
A MAC address is a 48-bit identifier, almost always written as six hex pairs. This tool randomly samples those 48 bits, then optionally flips two well-known control bits in the first octet — the unicast/multicast bit and the universal/locally-administered bit — and renders the result with your choice of separator and case.
For test data the right combination is usually "locally-administered, unicast" (U/L = 1, I/G = 0). That guarantees the address sits inside the slice IEEE reserved for private use and that it represents a single endpoint rather than a multicast group. Format conventions vary by vendor: colons on Linux/macOS, dashes on Windows, dots on Cisco gear — pick the form your tooling expects.
A MAC address whose second-least-significant bit of the first octet is 1 (e.g. 02:xx, 0a:xx, x6:xx). It signals that the address is not assigned by the IEEE registry — exactly what you want for randomly-generated test data, virtual interfaces, or per-device randomisation.
No. With 2^46 usable locally-administered unicast addresses, two random picks colliding is astronomically unlikely on small batches but not impossible. For a closed network you can verify uniqueness yourself; for the wider world, the OUI registry is the only authoritative source.
Functionally no — they are interchangeable. Convention varies by ecosystem: Linux and macOS print colons (aa:bb:cc:dd:ee:ff), Windows prints dashes (AA-BB-CC-DD-EE-FF), and Cisco IOS prints dots (aabb.ccdd.eeff). Pick whichever your target tooling expects.
Clearing the least-significant bit of the first octet to 0 marks the address as a unicast destination (a single device). Leaving it at 1 marks it as a multicast group address. Most randomly-generated test MACs should be unicast.
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