About MAC Address Vendor Lookup (OUI) – Offline
Every network interface ships with a MAC address, and its first three bytes — the OUI (Organizationally Unique Identifier) — are assigned by the IEEE to a specific manufacturer. This MAC address lookup tool reads that OUI and tells you which vendor made the hardware: Apple, Cisco, Intel, Samsung, a Raspberry Pi, an ESP32, and hundreds more.
It works on any format. Paste a colon, hyphen, dot (Cisco `0011.2233.4455`), or bare-hex MAC and the tool normalizes it, extracts the OUI, and runs the vendor lookup against a curated copy of the IEEE OUI registry bundled right into the page.
Because the dataset is local, the OUI lookup happens entirely offline — nothing you paste is ever sent to a server. That makes it safe to use on addresses pulled from packet captures, ARP tables, DHCP leases, or Wi-Fi scans without leaking anything.
Features
- Resolve the vendor of any MAC address from its OUI
- Accepts colon, hyphen, dot, and bare-hex formats
- Shows unicast vs multicast (I/G bit) and global vs local (U/L bit)
- Detects the broadcast address FF:FF:FF:FF:FF:FF
- Fully offline — the OUI dataset is bundled, nothing leaves your browser
How to use
- Paste or type a MAC address in any format.
- Read the resolved vendor, OUI, and the canonical normalized MAC.
- Check the flags for unicast/multicast and globally-unique/locally-administered.
- Copy any field with its copy button.
Frequently asked questions
What is an OUI?
The OUI (Organizationally Unique Identifier) is the first 24 bits — the first three bytes — of a MAC address. The IEEE assigns each OUI to one manufacturer, so it identifies who built the network interface.
Why does my lookup show "Unknown OUI"?
This tool bundles a curated subset of well-known OUIs rather than the full ~30,000-entry IEEE registry, so some valid prefixes are not listed. An unknown OUI still parses correctly — you just see the OUI and flags without a vendor name. It can also mean the address is randomized (locally administered).
What is the difference between unicast and multicast?
The least-significant bit of the first octet is the I/G bit. When it is 0 the address is unicast (one interface); when it is 1 it is multicast (a group). FF:FF:FF:FF:FF:FF is the special broadcast address.
What does "locally administered" mean?
The second-least-significant bit of the first octet is the U/L bit. When set, the address was assigned locally (for example a randomized Wi-Fi MAC) rather than from an IEEE-assigned OUI, so a vendor lookup may not be meaningful.
Is this MAC lookup tool private?
Yes. The OUI dataset is bundled into the page and the lookup runs in your browser, so no MAC address you enter is ever transmitted to a server.
Related tools
Everything runs locally in your browser — your input is never uploaded.