Is the MAC address sent anywhere for the lookup?

No. The address is analysed entirely in your browser and no network request is made, so the MAC is never transmitted. Vendor names come from a small built-in list, not a live query.

How are unicast, multicast, universal and local decided?

They come directly from the first octet's two lowest bits, as defined by IEEE 802. Bit 0 is the I/G bit (0 = unicast, 1 = multicast) and bit 1 is the U/L bit (0 = universally administered, 1 = locally administered). This is fully deterministic.

Why does my phone's Wi-Fi MAC show an unknown vendor?

Modern phones use randomised, locally-administered MAC addresses for Wi-Fi privacy. These have the U/L bit set and intentionally do not map to a real manufacturer, so the vendor will show as not in the local list.

An OUI (Organisationally Unique Identifier) is the first 3 octets (24 bits) of a MAC address. The IEEE assigns each OUI block to a manufacturer, so it identifies who made the network chip. The remaining 3 octets are the device-specific serial assigned by that manufacturer.

What MAC address formats are accepted?

Any common format works — colon-separated (3C:5A:B4:00:11:22), dash-separated, Cisco dotted (3c5a.b400.1122) or plain 12 hex digits. The tool strips all separators and reads the 12 hex characters, so spacing and case do not matter.

Does this tool find the vendor for every MAC address?

No. It uses a small curated list of common OUIs rather than the full IEEE registry, because a complete lookup would require a network request and this tool is deliberately offline. Common vendors like Apple, Google, Cisco, VMware and Raspberry Pi are covered; anything else is reported as not in the local list.

Can I tell a real device from a randomised address?

Yes — check the U/L (universal/local) bit. A universally administered address is a genuine factory OUI tied to a manufacturer. A locally administered address has the U/L bit set and is typically a randomised privacy MAC or a virtual NIC, with no real vendor.

What is the MAC Address Lookup?

Free MAC address lookup that decodes the OUI vendor prefix and the IEEE control bits of any EUI-48 MAC address, showing unicast vs multicast and universally vs locally administered. Analysed entirely in your browser with no lookup request — nothing is sent anywhere. It runs free in your browser on Gera Tools, with nothing uploaded.

MAC Address Lookup — Gera Tools

Name: MAC Address Lookup
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

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A MAC address (Media Access Control address) is the 48-bit hardware identifier burned into every network interface — your laptop’s Wi-Fi card, a phone, a router, a virtual machine. This lookup tool decodes any EUI-48 MAC address, telling you the manufacturer (when known), whether the frame is unicast or multicast, and whether the address is a real factory OUI or a randomised privacy address. It is useful for network admins identifying devices on a LAN, troubleshooting DHCP leases, or just sanity-checking why a phone shows an “unknown” vendor.

How it works

The address is normalised by stripping every non-hex character and upper-casing it, so colon (3C:5A:B4:00:11:22), dash, dot and plain 12-digit formats all work. The result must be exactly 12 hex digits (48 bits) split into six octets.

OUI — the first 3 octets form the Organisationally Unique Identifier. This is matched against a built-in vendor list; an OUI not in the list is reported as such rather than guessed.
I/G bit — bit 0 (least-significant) of the first octet. 0 = unicast, 1 = multicast (group address).
U/L bit — bit 1 of the first octet. 0 = universally administered (a real vendor OUI), 1 = locally administered (randomised or virtual).

Example

Take 3C:5A:B4:00:11:22. The first octet 3C is 0011 1100 in binary — bit 0 is 0 (unicast) and bit 1 is 0 (universally administered). The OUI 3C5AB4 maps to Google in the built-in list. So the result is: unicast, real vendor, Google.

By contrast 02:1A:2B:3C:4D:5E starts with 02 (0000 0010) — bit 1 is set, so it is locally administered: a randomised privacy MAC with no real manufacturer.

First octet bit	Name	0 means	1 means
bit 0	I/G	Unicast	Multicast
bit 1	U/L	Universal (real OUI)	Locally administered

Everything is computed in your browser — no lookup request is made, so the address is never sent anywhere. For a manufacturer not in the local list, consult the official IEEE OUI registry.