MAC Address Validator & Generator
NewValidate and reformat a MAC address between colon, hyphen, dot, and bare notation, decode its unicast/multicast and universal/local bits, or generate a random one.
———————This tool validates format, reformats between the common separator styles, and decodes the two bits that are always defined by the standard (unicast/multicast and universal/local). It does not look up the OUI's registered vendor — that requires IEEE's full OUI registry, which is too large to ship client-side and changes over time.
Frequently Asked Questions
What do the "unicast/multicast" and "universal/local" bits mean?
The least significant bit of a MAC address's first byte marks whether frames sent to it are unicast (one recipient) or multicast (a group). The second-least-significant bit marks whether the address is universally administered (factory-assigned by the vendor via its OUI) or locally administered (manually or randomly assigned) — both are always-defined parts of the IEEE 802 MAC address format.
Does this tool tell me the vendor/manufacturer of a MAC address?
No — that requires looking up the OUI (the first three bytes) against IEEE's full registered-vendor database, which is large and updated regularly, so it isn't shipped as a static client-side dataset in this tool. It shows you the raw OUI bytes so you can look them up elsewhere if needed.
Why does the random generator always set the "locally administered" bit?
This is the standard convention for software-generated MAC addresses (used by VMs, containers, and privacy-focused MAC randomization features) — it signals that the address wasn't assigned by a hardware vendor's registered OUI block, avoiding any collision with real hardware.
What formats does the reformatter support?
Colon-separated (00:1A:2B:3C:4D:5E), hyphen-separated (00-1A-2B-3C-4D-5E), Cisco-style dot notation (001A.2B3C.4D5E), and the bare unseparated hex string — covering the notations used across different vendors' tooling and operating systems.
Is my MAC address sent anywhere?
No — validation, reformatting, and random generation (via the Web Crypto API) all happen entirely in your browser.