MAC Address Lookup - Find the Vendor Behind an OUI

Paste a MAC address (or just the first three octets, the OUI prefix) to identify the manufacturer that registered it with the IEEE. The tool also normalizes the address and decodes its unicast/multicast and universally/locally-administered bits.

Related guide: What is a MAC address?

Accepts colons, hyphens, dots, or no separators (e.g. 00:1C:14, 00-1C-14, 001C14).

What is a MAC address and an OUI?

A MAC (Media Access Control) address is a 48-bit hardware identifier assigned to a network interface. It is usually written as six pairs of hexadecimal digits, for example 00:1C:14:2A:3B:4C. The first three octets (24 bits) form the OUI - the Organizationally Unique Identifier - which the IEEE assigns to a manufacturer. The remaining three octets are chosen by that manufacturer to make each device unique.

How vendor lookup works

Because every OUI is registered to one organization, you can map the first three octets of any MAC back to the company that built the interface. This tool extracts the OUI from your input and matches it against a dataset derived from the IEEE MA-L registry.

Understanding the address bits

  • Unicast vs. multicast - the least-significant bit of the first octet (the I/G bit). When it is 0 the frame is unicast; when it is 1 it is a group/multicast address.
  • Universal vs. local - the second-least-significant bit of the first octet (the U/L bit). When it is 0 the address is universally administered (vendor-assigned and globally unique); when it is 1 it is locally administered, which is what most devices use for MAC randomization on Wi-Fi.

Examples to try

  • 00:1C:14:00:00:01 - a VMware virtual NIC.
  • F0:EE:7A - an Apple OUI prefix.
  • D8:3A:DD:11:22:33 - a Raspberry Pi device.
  • 01:00:5E:00:00:01 - an IPv4 multicast address (note the multicast bit).

This tool matches against the full IEEE MA-L registry (~39,000 registered OUIs), refreshed from the official IEEE source.

Frequently Asked Questions

What does the MAC Address Lookup tool actually do?
It identifies the manufacturer that registered a network interface by reading the OUI - the Organizationally Unique Identifier, which is the first three octets (24 bits) of a MAC address. You can paste a full 48-bit MAC address (for example 00:1C:14:01:23:45) or just the OUI prefix (for example 00:1C:14). The tool extracts the OUI, matches it against a dataset derived from the IEEE MA-L registry, and shows the registered vendor name, a normalized version of the address, the OUI, and a decode of the unicast/multicast and universal/local bits.
What MAC address formats can I enter?
You can use colons, hyphens, dots, or no separators at all - for example 00:1C:14, 00-1C-14, or 001C14 all work. Internally the tool strips every non-hex character and keeps the result only if it is exactly 6 hex digits (a 24-bit OUI prefix) or 12 hex digits (a full 48-bit MAC address). Any other length is rejected with a message asking for a valid 48-bit MAC address or 24-bit OUI prefix.
Where does the vendor data come from, and how current is it?
Vendor names come from a static JSON dataset bundled with the site that is derived from the official IEEE MA-L registry (the source listed is standards-oui.ieee.org/oui/oui.csv), covering 39,476 registered OUIs. It is a snapshot generated on a fixed date, not a live query to the IEEE at the moment you search. Because it covers the MA-L registry, smaller MA-M and MA-S blocks and very recently registered prefixes may not be present, in which case the tool reports the vendor as not found in the IEEE registry.
Why does it say no vendor was found for some addresses?
There are two cases the tool surfaces directly. First, the OUI may be structurally valid but simply not present in the bundled MA-L dataset - for example an unregistered, reserved, or privately assigned prefix. Second, the address may be locally administered (the U/L bit is set), which means it was randomized or manually assigned rather than vendor-issued, so it is not registered to any manufacturer. The tool detects both cases and explains which one applies.
What do the unicast/multicast and universal/local labels mean?
The tool reads two flag bits from the first octet of the address. The I/G bit (least-significant bit) determines address scope: it reports Unicast when the bit is 0 (sent to a single interface) or Multicast/group when it is 1. The U/L bit (second-least-significant bit) determines administration: Universally administered when the bit is 0 (vendor or IEEE assigned and globally unique) or Locally administered when it is 1 (typically MAC randomization on Wi-Fi or a manually set address). These labels are computed locally from the address itself, and the vendor is resolved against the bundled dataset with no external API call for the lookup.
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How this tool works: This tool runs in your browser and on our server in real time. Depending on the tool, results are computed directly from the input you provide or retrieved from live, authoritative data sources at the moment you run a lookup. We do not sell your data, and your lookups are kept private — any history shown here is stored only on your device.

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