MAC Address Lookup
Look up the vendor of any MAC address against the built-in IEEE OUI database, normalize every input format, inspect the I/G and U/L flag bits and derive the EUI-64 link-local address — with a random locally administered MAC generator, all offline.
What can this MAC lookup tell me?
Paste any MAC address and the tool shows the normalized form, the three-byte OUI prefix, the vendor registered in the IEEE OUI database, the meaning of the I/G and U/L flag bits, and the EUI-64 interface ID with its fe80:: link-local address.
Which MAC formats does it accept?
Colon separated (00:1A:2B:3C:4D:5E), hyphen separated (00-1A-2B-3C-4D-5E), Cisco dotted (001A.2B3C.4D5E) and bare hex (001a2b3c4d5e) all work, in upper or lower case. Sixteen hex digits (8-byte MACs) are also accepted.
What do the I/G and U/L bits mean?
The lowest bit of the first byte is the Individual/Group flag: 0 means a unicast address for one device, 1 means multicast or broadcast. The second-lowest bit is Universal/Local: 0 means the vendor burned the address into the hardware, 1 means it was assigned by software.
How is the EUI-64 link-local address derived?
The 48-bit MAC is split in half, ff-fe is inserted in the middle and the seventh bit (U/L) is flipped, producing a 64-bit interface ID. Prefixed with fe80:: it becomes the address a device can use for local IPv6 communication without a DHCP server.
Why does my MAC show no vendor?
The prefix may not be assigned yet, may belong to a private range used inside a company, or may be locally administered by virtualization or privacy software such as phone MAC randomization. The message will tell you when the database has no entry.
What does the Random MAC button do?
It generates a random 48-bit address with the locally administered bit set to 1 and the multicast bit cleared to 0 — the kind of address operating systems create for Wi-Fi privacy. Copy it and use it wherever you need a placeholder address.
Does the lookup send my MAC to a server?
No. The entire IEEE OUI database is embedded in the page, so the vendor search, flag analysis and EUI-64 math all run locally in your browser. Nothing is uploaded and no account is needed.
How current is the vendor database?
It is a snapshot of the official IEEE oui.txt file converted at build time, covering roughly 40,000 registered prefixes. Newly assigned prefixes after that snapshot will show as not found until the data is refreshed.
How to Use MAC Address Lookup
This tool identifies the hardware vendor behind any MAC address using a full copy of the IEEE OUI database embedded in the page. Type an address in colon, hyphen, Cisco dotted or bare hex form and it normalizes the input, resolves the three-byte OUI prefix to a company name, explains the I/G and U/L flag bits and derives the EUI-64 interface ID with its fe80:: link-local address. A random locally administered MAC generator is one click away, and everything runs offline in your browser.
- Paste or type a MAC address in any common format, for example 00:1A:2B:3C:4D:5E, 00-1A-2B-3C-4D-5E, 001A.2B3C.4D5E or 001a2b3c4d5e.
- Read the normalized address and OUI prefix chips under the input — they confirm how the input was interpreted.
- The wide vendor card shows the company registered for the prefix in the IEEE OUI database, or a clear message when the prefix has no entry.
- Check the two flag cards: the I/G bit tells unicast from multicast and the U/L bit tells a burned-in vendor address from a locally administered one.
- Use the EUI-64 card to get the interface ID and fe80:: link-local address for the device, or press Random MAC to generate a locally administered address for testing.
Phone MAC randomization and virtual machines usually produce locally administered addresses (U/L bit = 1) with no OUI vendor — if the lookup misses, that is the most likely reason. Sixteen-digit (8-byte) MACs are accepted too; their first three bytes still resolve to a vendor.
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