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MAC address generator

Generate random, well-formed MAC addresses in colon, hyphen or Cisco notation.

Output

MAC address generator

Generate one random MAC address or a list of thousands, each on its own line and ready to paste into a config file, test fixture or spreadsheet. Four notations are available: colon-separated pairs (aa:bb:cc:dd:ee:ff), hyphen-separated pairs as Windows prints them, Cisco's dotted groups of four (aabb.ccdd.eeff) and bare hex with no separators. A checkbox switches between lowercase and uppercase.

The interesting part of a MAC address is its first byte, and this generator gets it right. With "Locally administered" on — the default — every address has its U/L bit set, marking it as locally assigned. Such addresses are the correct choice for generated values because they can never collide with the vendor-assigned OUI ranges real hardware uses; it is the same convention virtual machines and privacy-conscious phones follow. Untick it to produce OUI-style, globally-unique-looking addresses for parsers that expect them. The "Unicast" checkbox controls the I/G bit the same way, and turning it off yields multicast addresses for testing that corner of your code.

Typical uses: seeding a device database, populating DHCP reservations in a lab, fuzzing a network-inventory parser, writing documentation examples that are obviously not real hardware, or configuring a VM when the hypervisor asks for a MAC.

Every byte comes from crypto.getRandomValues and the whole tool runs locally in your browser — nothing is uploaded, logged or stored. Note that the tool generates values; actually changing a network interface's MAC is done in your operating system.

FAQ

Is anything sent to a server?
No. The addresses are generated in your browser with the Web Crypto API and never leave your device.
What does "Locally administered" mean?
It sets the U/L bit in the first byte, marking the address as locally assigned rather than vendor-assigned. Generated addresses should keep it on: they can then never collide with a real device's OUI-based address.
Can a generated address clash with real hardware?
With "Locally administered" on, no — that address space is reserved for local assignment and vendors never ship hardware in it. With it off, a collision with some vendor's range is theoretically possible, so use those only as test data.
Which format do Cisco devices use?
Cisco IOS prints MAC addresses as three dot-separated groups of four hex digits, like aabb.ccdd.eeff. Pick the Cisco option to match it.
Does this change my computer's MAC address?
No. It only generates values. Changing an interface's MAC is an operating-system setting — macOS, Windows and Linux each have their own way to do it.