# MAC OUI Vendor Lookup Look up the manufacturer of a MAC address from the IEEE OUI database, or reverse-search a company name to list all its OUI blocks — fully offline > Canonical page: https://elysiatools.com/en/tools/mac-oui-vendor-lookup - **Category:** Network - **Keywords:** mac, oui, vendor, manufacturer, ieee, network, ethernet, wifi, hardware address, arp ## Overview Two modes against a bundled offline copy of the IEEE OUI database (39,227 OUI blocks): (1) MAC address → vendor — parses any common format, decodes the OUI, shows the registered organization/address and the address type (UAA / locally administered / multicast) from the U/L and I/G bits, plus format conversions; (2) Company name → OUI list — tokenized reverse search returning all OUI blocks registered to matching organizations, grouped by company. ## Inputs - **Lookup Mode** (select) - **Input** (text): Forward: 00:1A:2B:3C:4D:5E · Reverse: Apple - **Max reverse results** (number) ## When to use - When analyzing network traffic logs or ARP tables and you need to identify the physical manufacturers of connected devices. - When auditing network security and verifying whether MAC addresses belong to legitimate hardware vendors or are locally administered/randomized. - When researching hardware vendor allocations to find all OUI blocks registered to a specific company like Apple, Cisco, or Intel. ## How it works - Select your lookup mode: choose 'MAC address → vendor' to identify a manufacturer, or 'Company name → OUI list' to find registered blocks. - Enter your input, which can be a MAC address in any standard format (colon, hyphen, Cisco dot notation, or raw hex) or a company name. - The tool parses the input offline against the IEEE OUI database, decodes the U/L and I/G bits to determine the address type, and outputs the matching vendor details or OUI list. ## Use cases - Identifying unknown devices on a local network by looking up their MAC addresses from an ARP table or DHCP lease list. - Generating a comprehensive list of OUI prefixes owned by a specific network hardware manufacturer for firewall or IDS configuration. - Decoding MAC address bits to verify if a device is using a randomized, locally administered, or multicast address. ## Frequently asked questions ### What formats of MAC addresses does the tool support? The tool supports all common MAC address formats, including colon-separated (00:1A:2B:3C:4D:5E), hyphen-separated (00-1A-2B-3C-4D-5E), Cisco dot notation (001a.2b3c.4d5e), and raw hexadecimal strings. ### What is the difference between UAA and locally administered MAC addresses? A Universally Administered Address (UAA) is globally unique and assigned by the IEEE to the manufacturer. A locally administered address is generated by software (like VMs or mobile MAC randomization) and will not appear in the IEEE OUI database. ### Does this tool require an active internet connection? No, the tool runs entirely offline in your browser using a bundled copy of the IEEE OUI database containing over 39,000 registered blocks. ### Why does a valid MAC address show as 'not found' or unknown vendor? This usually happens if the MAC address is locally administered (randomized), or if it belongs to a newer small-block allocation (MA-M, MA-S, or IAB) that falls outside the classic 24-bit OUI prefix matching. ### How many results can I retrieve when reverse-searching by company name? You can configure the tool to return up to 500 matching OUI blocks per search, grouped by the registered organization name. ## Related tools - [NB-IoT LTE-M Cat-M1 CoAP LwM2M Cellular IoT Packet Analyzer](https://elysiatools.com/en/tools/nb-iot-lte-m-cat-m1-coap-lwm2m-cellular-iot-packet-analyzer): Decode hex captures from cellular IoT devices: CoAP headers/options (block-wise, Observe), LwM2M TLV object trees with registry names, SMS-DELIVER UDH port addressing unwrapping CoAP-over-SMS, link-format registrations and DTLS record summaries. - [DNSSEC Chain & RDAP Trust Auditor](https://elysiatools.com/en/tools/whois-rdap-dnssec-chain-validator-and-iana-bootstrap-trust-auditor): Audit a domain end to end: IANA RDAP bootstrap referral, registry/registrar WHOIS data, and the DNSSEC chain of trust from the root KSK through the TLD DS to the apex DNSKEY — with DS digest verification and RRSIG expiry flags. - [Integer to IPv4](https://elysiatools.com/en/tools/integer-to-ipv4): Convert integers to IPv4 addresses. Supports batch conversion of multiple integers. - [IPv4 to Integer](https://elysiatools.com/en/tools/ipv4-to-integer): Convert IPv4 addresses to integers. Supports batch conversion of multiple addresses. - [Integer to IPv6](https://elysiatools.com/en/tools/integer-to-ipv6): Convert integers (128-bit) to IPv6 addresses. Supports batch conversion. - [IPv4 to IPv6](https://elysiatools.com/en/tools/ipv4-to-ipv6): Convert IPv4 addresses to IPv6 addresses. Supports IPv4-mapped and IPv4-compatible formats. - [IPv6 to Integer](https://elysiatools.com/en/tools/ipv6-to-integer): Convert IPv6 addresses to integers (128-bit). Supports batch conversion. - [IP Geolocation](https://elysiatools.com/en/tools/ip-geolocation): Visualize the geographic location, network (ASN/ISP), timezone, and security posture of any IP address as a rich card report ## Samples - [MAC Address Samples](https://elysiatools.com/en/samples/mac-address): Collection of MAC addresses in various formats for validation testing - [Web Image Processing Python Samples](https://elysiatools.com/en/samples/web-image-processing-python): Web Python image processing examples using PIL/Pillow including reading, saving, resizing, and format conversion - [Android Image Processing Java Samples](https://elysiatools.com/en/samples/android-image-processing-java): Android Java image processing examples including reading/saving images, scaling, and format conversion - [Android Image Processing Kotlin Samples](https://elysiatools.com/en/samples/android-image-processing-kotlin): Android Kotlin image processing examples including reading/saving images, scaling, and format conversion