MAC Address Lookup – Vendor, OUI & Randomized MAC Checker

Free Online MAC Address Vendor Lookup

The Utiliverse MAC Address Lookup identifies the organization associated with a MAC address prefix and explains the address itself. A standard MAC address is 48 bits, or 6 bytes, and is typically written as 12 hexadecimal digits. The manufacturer portion comes from an IEEE-assigned prefix, while the remaining bits identify an interface within that allocation.

The tool accepts colon-separated, hyphen-separated, Cisco-style, and separator-free formats. It also exposes assignment metadata returned by the live vendor database, including MA-L, MA-M, or MA-S block types when available.

How to Use the MAC Address Lookup

Enter a full MAC address or OUI prefix

Paste the address exactly as you found it. You can also enter only the first six hexadecimal digits when you need an OUI lookup.

Identify the manufacturer

Utiliverse queries a public MAC vendor database and displays the organization assigned to the matching IEEE address block. If the detailed lookup service is temporarily unavailable, a second browser-compatible vendor service is used as a fallback. Vendor results describe the block owner, not necessarily the brand printed on the finished device.

Understand the OUI and IEEE block

The classic OUI is the first 24 bits of many MAC assignments. Modern IEEE allocation types can use other prefix lengths, and the returned block type may identify a more specific MA-L, MA-M, or MA-S assignment.

Check globally unique versus locally administered

The U/L bit in the first octet indicates whether the address is globally administered or locally administered. Locally administered addresses are common with MAC randomization, virtual adapters, containers, and manually configured interfaces.

Check unicast versus multicast

The I/G bit in the first octet distinguishes an individual unicast address from a group multicast address.

Review vendor block details

When available, the result includes the beginning and end of the assigned block, the allocation size, country code, and vendor-record update date. These describe the registered allocation, not the current physical location of a device.

Convert between MAC formats

The normalized-format section shows colon-separated, hyphen-separated, Cisco dotted, and plain hexadecimal versions for easy use across Windows, Linux, macOS, switches, routers, and firewalls.

MAC Address, OUI & Vendor Lookup Reference

A MAC address is usually a 48-bit identifier written as 12 hexadecimal digits. Vendor lookup commonly starts with the leading IEEE-assigned portion of the address, often referred to as the OUI. The exact registered prefix length can vary with modern IEEE assignment types, so a vendor result should be treated as address-block ownership information rather than proof of an exact device model.

Common MAC address formats

What is an OUI?

An OUI, or Organizationally Unique Identifier, is traditionally the first 24 bits of a MAC address block assigned to an organization. Many vendor lookups use this prefix to identify the organization associated with a MAC address. Modern IEEE assignment types can use different prefix lengths, so the first six hexadecimal digits are a useful lookup shortcut but not always the complete registered boundary.

MAC vendor lookup versus exact device identification

A vendor match can tell you which organization is associated with an address block, but it usually cannot identify the exact model, serial number, owner, hostname, or physical location. MAC addresses can also be randomized, virtualized, cloned, or spoofed.

Randomized and private MAC addresses

Modern phones, tablets, laptops and other devices may use private or randomized MAC addresses on Wi-Fi networks. These commonly use locally administered addressing, which means the U/L bit indicates that the address was assigned locally rather than directly from globally administered IEEE address space. A locally administered address can also come from a virtual machine, container, test setup, or manual configuration.

Locally administered does not always mean randomized

A locally administered MAC is compatible with Wi-Fi privacy randomization, but it can also be used by virtualization software, containers, locally configured network interfaces, lab equipment, or other software-defined networking systems. The bit pattern is a clue, not proof of how the address was created.

Vendor country is not device location

Country and street-address fields returned by vendor databases describe registration information associated with the organization or assignment record. They do not reveal where the device itself is currently located.

Lookup Methodology, Address Bits, and Important Limits

The tool first normalizes the entered value by converting it to uppercase and removing every character that is not a hexadecimal digit. It accepts either a 6-digit prefix or a complete 12-digit MAC address. Local address characteristics and normalized formats are calculated in the browser before any vendor result is rendered.

Worked example: locally administered unicast

Worked example: multicast bit

Worked example: format normalization

Locally administered does not automatically mean randomized Wi-Fi

The tool treats the U/L bit as a local-address indicator and also surfaces an API isRand flag when provided. A locally administered address can come from private Wi-Fi randomization, a virtual machine, a container, manual configuration, test equipment, or another locally assigned mechanism. The bit pattern alone cannot identify which one.

Vendor lookup identifies an assignment owner, not an exact device

A vendor match describes the organization associated with an IEEE address block or vendor database record. It does not identify the exact model, serial number, user, device owner, current hostname, or physical device location.

Country and vendor address are registry metadata, not geolocation

Country and address fields describe information associated with the vendor registration returned by the lookup service. They do not show where the device is physically located or where the network traffic originated.

The primary lookup uses JSONP with a timeout

The detailed lookup creates a temporary script element pointing to MACLookup.app's JSONP endpoint. A unique callback name is registered in the page, referrerPolicy is set to no-referrer, and the request is treated as failed if it does not complete within 9 seconds.

The fallback lookup returns less metadata

If the detailed service fails, the tool sends a CORS GET request to macadress.com's vendor endpoint with its own 9-second abort timeout. A successful fallback typically provides a vendor name plus the locally computed MAC characteristics. Country, block range, assignment type, address, and registry-update fields can remain blank because the fallback does not supply those details.

A fallback 404 is not always the same as “invalid”

For the fallback service, HTTP 404 is converted into a valid “not found” result. If the U/L bit indicates a local address—or the response text describes a locally administered address—the page labels it accordingly. Otherwise it reports that no registered vendor was found.

Local analysis still works when both vendor services fail

Even if both network services are unreachable, the tool still knows how to normalize the address, determine U/L and I/G bit characteristics, and show locally administered information. Network failure does not prevent those purely local calculations.

OUI output is a practical prefix display

If the detailed API returns a macPrefix, the page formats that value. Otherwise it uses the first six hexadecimal digits of the supplied input as a traditional 24-bit OUI-style prefix. Modern IEEE allocations can use MA-L, MA-M, or MA-S blocks with different prefix lengths, so the first 24 bits should not always be interpreted as the exact registered allocation boundary.

Vendor block formatting depends on the returned value

When a returned block start or end contains 12 hexadecimal digits, the page normalizes it to colon-separated MAC format. Other returned representations are displayed in a simpler cleaned form. Block size is displayed as metadata from the external service rather than recalculated locally.

MAC addresses can be spoofed or cloned

Software, virtual machines, network appliances, and many operating systems can change or emulate MAC addresses. A globally administered-looking prefix can be copied onto another interface, and a vendor-looking match does not prove that the device was manufactured by that organization.

Common mistakes

• Assuming a vendor match reveals the exact hardware model.
• Treating vendor country metadata as the device's current location.
• Assuming every locally administered address is definitely a private Wi-Fi address.
• Assuming a vendor-looking prefix cannot be spoofed or cloned.
• Interpreting a failed vendor lookup as proof that the MAC address itself is invalid.

Related Utiliverse Tools

Last reviewed: October 3, 2026 · Input normalization, 6/12-digit validation, U/L and I/G bit logic, normalized formats, MACLookup.app JSONP behavior, fallback CORS request, timeout handling, locally administered fallback, vendor metadata rendering, copy/reset, and theme behavior reviewed against the current implementation.

Practical Uses

Identify unknown devices

Vendor data can help narrow down an unfamiliar device shown by a router, access point, switch, DHCP lease table, or network monitor. Randomized addresses can make this less conclusive.

Network inventory

Administrators can compare DHCP leases, switch forwarding tables, wireless clients, and monitoring data with vendor assignments.

Virtual machine identification

Virtualization products often use recognizable MAC ranges, making vendor lookup useful in server and lab environments.

Security investigations

Vendor information is useful context but not proof of identity because MAC addresses can be changed, spoofed, or locally generated.

Documentation and DHCP reservations

Use the format converter to reduce transcription errors when recording devices, configuring reservations, or copying addresses between systems that use different notation.

MAC Address Lookup FAQ