MAC Address Lookup
Paste a MAC address to find the hardware vendor from the IEEE OUI registry, and see whether it is a globally unique or locally administered address. The lookup table loads once and then runs entirely in your browser.
Lookups use the public IEEE OUI registry (via the Wireshark manuf list). A randomized or locally administered address has the second-least-significant bit of the first octet set and usually will not match a vendor.
What the first half of a MAC tells you
The first three bytes of a MAC address are the OUI (Organizationally Unique Identifier), assigned to the maker by the IEEE. That is how an unknown device on your network resolves to Intel, Apple, Raspberry Pi, Ubiquiti, and so on. The last three bytes are assigned by the vendor to the individual NIC.
One catch worth knowing: phones and some operating systems now use randomized MACs for privacy. Those set the locally administered bit and will not map to a real vendor, which is flagged in the result above. That is expected, not a failed lookup.
Tracking devices down on your LAN usually starts at the firewall or router. pfSense vs OPNsense covers the two that give you the best visibility, and the subnet calculator helps you map the address ranges they live in.