MAC OUI Lookup
Look up a Media Access Control (MAC) address's first 3 octets in the IEEE Organizationally Unique Identifier (OUI) vendor database (curated subset).
Curated subset of 111 well-known OUIs (full IEEE database is ~5 MB / ~30k entries — can be bundled in a follow-up if needed).
Monitor MAC OUI Lookup automatically
Look up a Media Access Control (MAC) address's first 3 octets in the IEEE Organizationally Unique Identifier (OUI) vendor database (curated subset). NetTests can run this check on a schedule, preserve historical results, compare changes over time, and alert you the moment something breaks.
Start monitoring free → See all monitoring productsFrequently Asked Questions
What is a MAC OUI?
An Organizationally Unique Identifier (OUI) is the first three octets of a Media Access Control (MAC) address, assigned by the Institute of Electrical and Electronics Engineers (IEEE) to device manufacturers. For example, 00:1A:2B identifies the manufacturer who registered that prefix. This tool looks up the OUI in the IEEE database to identify which company made a network interface card.
What can I determine from a MAC address?
The Organizationally Unique Identifier (OUI) identifies the manufacturer of the network hardware — useful for network inventory, device identification, and troubleshooting. The remaining 3 octets are device-specific and assigned by the manufacturer. You cannot determine a device's Internet Protocol (IP) address, location, or owner from a Media Access Control (MAC) address alone.
Why doesn't the OUI always match the actual device maker?
Several reasons: the Organizationally Unique Identifier (OUI) may belong to a chip manufacturer (e.g. Broadcom or Qualcomm) rather than the device brand (e.g. a laptop maker using their WiFi chip's OUI). Virtual machines use OUIs assigned to VMware, VirtualBox, or Hyper-V. Randomized Media Access Control (MAC) addresses (used by iOS, Android, and modern Windows for privacy) will not match any real manufacturer.