IEEE OUI Database - Data Source

Website	https://standards-oui.ieee.org/
Category	Browser Security & Hardware

The IEEE OUI (Organizationally Unique Identifier) database is the authoritative registry mapping the first three bytes of MAC addresses to the hardware manufacturers that own them. Maintained by the Institute of Electrical and Electronics Engineers (IEEE), this database is the foundation of MAC address vendor identification worldwide.

Source:IEEE OUI Database

What is the IEEE OUI Database?

Every network interface card (NIC) is assigned a unique 48-bit MAC address. The first 24 bits of this address form the OUI, a prefix assigned by IEEE to the organization that manufactures the device. For example, the OUI 00:1A:2B might belong to Apple, meaning any device with a MAC address starting with those bytes was manufactured by Apple.

IEEE maintains three registration tiers: MA-L (MAC Address Block Large) provides a full 24-bit OUI with 16.7 million unique addresses per assignment. MA-M (Medium) assigns 28-bit blocks with roughly one million addresses. MA-S (Small) assigns 36-bit blocks with 4,096 addresses. Most well-known manufacturers hold MA-L registrations, often multiple ones as they exhaust address space.

The database contains approximately 30,000 registered entries from manufacturers around the world, ranging from consumer electronics giants like Samsung, Apple, and Intel to specialized industrial equipment makers, IoT device vendors, and telecommunications companies. New registrations are processed by IEEE on an ongoing basis as manufacturers request address space for new product lines.

How We Use This Data

Our MAC address lookup tool uses the IEEE OUI database to identify the manufacturer behind any MAC address. Enter a full MAC address like D8:A3:5C:12:34:56 or just the three-byte OUI prefix D8:A3:5C, and we resolve it to the registered manufacturer, including their company name and country of registration.

This is useful for network administration (identifying unknown devices on your network), security auditing (spotting unauthorized or unexpected hardware), and general troubleshooting. The data is imported from IEEE's official public registry files and kept synchronized with upstream changes.

FAQ

What does OUI stand for and how does it relate to MAC addresses?

OUI stands for Organizationally Unique Identifier. It is the first three bytes (24 bits) of a MAC address, assigned by IEEE to hardware manufacturers. When you see a MAC address like D8:A3:5C:12:34:56, the OUI portion is D8:A3:5C, which identifies the manufacturer. The remaining three bytes are assigned by the manufacturer to each individual device they produce.

Why does my device's MAC address not match any vendor in the database?

Modern operating systems use MAC address randomization for privacy. iOS, Android, Windows, and macOS generate random locally-administered MAC addresses for Wi-Fi connections to prevent cross-network tracking. Randomized addresses have the second-least-significant bit of the first byte set to 1 (the "locally administered" flag), indicating they are not assigned by IEEE. Your device's real hardware MAC can be found in system settings.

How is the IEEE OUI database different from other MAC lookup services?

The IEEE database is the primary authoritative source. All other MAC vendor lookup services ultimately derive their data from IEEE's registrations. We import directly from IEEE's official registry files, ensuring accuracy and completeness. Some third-party databases add supplementary information like device types or model guesses, but the core vendor identification always traces back to IEEE OUI assignments.