MAC / OUI Vendor Lookup
Identify the manufacturer for a MAC address's first 3 bytes.
Overview
The MAC / OUI vendor lookup identifies the manufacturer of a network interface from the first three octets of its MAC address — the Organisationally Unique Identifier (OUI). Paste a MAC like B8:27:EB:01:02:03 and the tool returns the registered vendor (Raspberry Pi Foundation, in that case) plus a note on whether the address is universally or locally administered.
System administrators sweeping a LAN for unknown devices, security analysts identifying suspicious hardware in DHCP logs, and IT support staff tracing a stray laptop all need an OUI lookup. Long-tail keywords covered: identify device manufacturer from MAC address, lookup OUI vendor online, and detect locally administered MAC address.
How it works
A MAC address is 48 bits, written as six hex octets. The IEEE allocates the first three octets (the OUI) to manufacturers; the remaining three octets are assigned per-device by that vendor. Three flag bits within the OUI carry metadata: the U/L bit (universally vs locally administered) and the I/G bit (individual vs group / multicast). A locally administered address — common on virtual NICs and randomised mobile Wi-Fi — does not match any vendor.
The IEEE publishes the OUI registry as a regularly updated CSV. The tool ships with a snapshot of common entries and falls back to "Unknown / private" for OUIs that are unassigned, locally administered, or part of the MA-S and MA-M smaller allocations that overlap with the OUI prefix.
Examples
B8:27:EB:xx:xx:xx→ Raspberry Pi Foundation.00:1A:11:xx:xx:xx→ Google, Inc.FC:FB:FB:xx:xx:xx→ Cisco Systems.02:00:00:00:00:01→ locally administered (the U/L bit is set), no vendor.
FAQ
Why does my phone return a different vendor every scan?
Modern smartphones randomise their Wi-Fi MAC address per network for privacy. The randomised addresses are flagged as locally administered and never resolve to a real vendor.
What is the difference between OUI, MA-L, MA-M, and MA-S?
MA-L is the classic 24-bit OUI (16M addresses per assignee). MA-M is 28 bits (1M per assignee). MA-S is 36 bits (4,096 per assignee). Small allocations let the IEEE serve manufacturers that need fewer addresses.
Can two vendors share an OUI?
No. Each OUI is exclusively assigned to one organisation, though organisations may have multiple OUIs.
How fresh is the data?
The bundled snapshot is updated periodically. Brand-new vendor registrations may be missing for a few weeks after their initial assignment.