Paste a full MAC or just the 24-bit OUI. Returns the registered organization, splits the address into OUI and NIC halves, and decodes the I/G and U/L flags — checked against a local IEEE copy and live registries.
A MAC address is 48 bits, written as six hex octets. The first 24 bits are the OUI — the block IEEE assigns to a vendor — and the last 24 are the NIC-specific portion the vendor assigns per interface. Resolving the OUI against the IEEE registry is what identifies the manufacturer.
The first octet also carries two flag bits that change what the address means:
| Bit | Position | 0 | 1 |
|---|---|---|---|
| I/G | octet 1, bit 0 | unicast | multicast / group |
| U/L | octet 1, bit 1 | globally unique (OUI) | locally administered |
When the U/L bit is set, the address was assigned by software (a VM, a randomized Wi-Fi MAC, a bonded interface) and has no registered vendor — which is why a lookup can legitimately return nothing. The tool decodes these bits so you can tell the difference at a glance.
No single registry is always complete or online. Lookups resolve in order: a local IEEE copy, then a seed cache, then the live registries maclookup.app and macvendors.com — each with a timeout, falling through on failure. The result shows which source answered.
Yes — that's the OUI. Enter 00065B to identify the vendor without a full address. The NIC half will show as unassigned.
The I/G bit marks the frame target: 0 = unicast, 1 = multicast/group. The U/L bit marks the address origin: 0 = globally unique (IEEE OUI), 1 = locally administered (set by software). A locally administered address has no real vendor.
The U/L bit is set (locally administered), the OUI sits in an unassigned block, or it's a privacy-randomized address from a phone. These aren't errors — there's simply no registered owner.
Linux: ip link. macOS: ifconfig en0. Windows: getmac /v or ipconfig /all.