What this tool does
The first 24 bits (3 octets) of a MAC address are the Organizationally Unique Identifier (OUI), assigned by the IEEE to a specific hardware manufacturer. This tool looks up that prefix against a vendor database and returns the manufacturer name.
When you'd use this
Identifying unknown devices on a network scan, auditing a DHCP lease table for unauthorized hardware, or confirming that a device claiming to be a specific vendor's product actually has a MAC prefix that matches.
A note on locally administered addresses
Not every MAC address maps to a real manufacturer — devices can use locally administered addresses, and virtual machines, containers, and privacy-focused mobile OSes increasingly randomize MAC addresses for Wi-Fi scanning to prevent tracking. A lookup returning no vendor doesn't necessarily mean anything is wrong.
What is an OUI, exactly?
The Organizationally Unique Identifier is the first half of a MAC address (24 of the 48 bits, shown as the first three hex octet pairs) that the IEEE assigns to hardware manufacturers in blocks. A vendor with a large product line may hold dozens of OUI blocks; a small manufacturer might have just one. The remaining 24 bits are assigned by the manufacturer itself to uniquely identify each individual device they produce.
Finding a device's MAC address
On most operating systems this is available via a network settings screen or a quick terminal command -- `ipconfig /all` on Windows, `ifconfig` or `ip link` on Linux/macOS. On a router's admin page, it usually shows up in the connected-devices or DHCP client list, often labeled "physical address" or "hardware address."