ToolsOpsNetworking
MAC vendor and OUI lookup
Paste or type a MAC address (colon, dash, no separator or Cisco dotted) or a 24-bit OUI. The tool normalizes the format, identifies the vendor against a snapshot of the IEEE registry embedded in the page and flags locally administered, multicast, broadcast and all-zero addresses with an explanatory note. Nothing is sent to any server.
MAC address or OUI
Accepts colon (00:1A:2B:3C:4D:5E), dash (00-1A-2B-3C-4D-5E), no separator (001A2B3C4D5E), Cisco dotted (001A.2B3C.4D5E) and 24-bit OUI.
Your MAC never leaves the browser
The whole lookup runs inside your tab against a snapshot of the IEEE registry embedded in the page. We do not upload the address to any server, we do not store it and we do not forward it to third parties.
Paste or type a MAC address to identify the vendor.
How to use the MAC vendor lookup
This tool accepts a full MAC address or a 24-bit OUI and returns the vendor (when present in the embedded snapshot), the canonical form of the value, the assignment kind and a semantic classification (locally administered, multicast, broadcast or all-zero).
When the address has no associated vendor, the tool does not simply say "unknown": it classifies the reason (LAA, multicast, broadcast, all-zero or just "outside the snapshot") and explains why with a contextual note.
| Format | Example | Notes |
|---|---|---|
Colon | 00:1A:2B:3C:4D:5E | Unix/Linux standard; recommended. |
Dash | 00-1A-2B-3C-4D-5E | Windows standard (ipconfig). |
No separator | 001A2B3C4D5E | Logs and databases. |
Cisco dotted | 001A.2B3C.4D5E | IOS / IOS-XE show interface. |
OUI colon | 00:1A:2B | 24-bit prefix only. |
OUI plain | 001A2B | 24-bit prefix only, no separator. |
What is an OUI
An OUI (Organizationally Unique Identifier) is a 24-bit prefix IEEE assigns to vendors so they can generate unique MAC addresses. IEEE also assigns longer prefixes — MA-M (28 bits) and MA-S (36 bits) — for vendors with lower production volumes, but most historical OUIs are MA-L 24-bit blocks.
- MA-L (24 bits): large block, classic assignment. Over 36,000 records.
- MA-M (28 bits): medium block. ~5,000 records.
- MA-S (36 bits): small block. ~16,000 records.
- This MVP only queries its curated MA-L snapshot; MA-M and MA-S are not included yet.
Global vs locally administered MAC
The second bit of the first octet (the U/L bit) decides whether an address is assigned by IEEE to a vendor (=0, universally unique) or by a local administrator (=1). Addresses like 02:xx:xx:xx:xx:xx or 06:xx:xx:... are the most recognisable LAA cases because the first octet's pattern marks the bit clearly.
Modern iPhones, MacBooks and Android devices use randomized LAA addresses to prevent cross-network Wi-Fi tracking. When a MAC is LAA, do not expect a vendor: it is deliberately non-attributable.
Why a vendor may not show up
Three common reasons explain a no-vendor result in this tool:
- Locally administered: the address does not originate from IEEE.
- Partial snapshot: the full IEEE listing has >36,000 entries; this MVP only ships the most common vendors as an initial snapshot.
- Recent assignment: the OUI may have been registered after the embedded snapshot was generated.
Multicast, broadcast and reserved ranges
Some addresses do not represent a physical host but a group or a special destination:
- Broadcast FF:FF:FF:FF:FF:FF: reaches every node on the segment.
- All-zero 00:00:00:00:00:00: not a valid assignment; shows up as a placeholder.
- IPv4 multicast 01:00:5E:*: L2 mapping for IPv4 multicast (RFC 1112).
- IPv6 multicast 33:33:*: L2 mapping for IPv6 multicast (RFC 2464).
- VRRP 00:00:5E:00:01:*: virtual MAC for Virtual Router Redundancy Protocol.
- STP/LACP 01:80:C2:*: Spanning Tree BPDUs and LACP aggregations.
Privacy — what this tool does and does not do
The lookup runs entirely in your browser against a snapshot of the IEEE registry embedded in the page. The MAC address is never sent to any server, not stored in localStorage, not forwarded to third parties. To share a result, use the copy buttons.
What this tool does NOT do: it does not geolocate a device from its MAC. MAC addresses only travel inside a local network segment (Wi-Fi, Ethernet, LAN). Services that claim to "geolocate" a public MAC are selling scanned Wi-Fi network databases, not the MAC itself.
Frequently asked questions
- What is an OUI?
- An OUI (Organizationally Unique Identifier) is a 24-bit prefix that IEEE assigns to a manufacturer so they can generate unique MAC addresses. The remaining 24 bits are managed by the vendor. IEEE also issues longer prefixes — MA-M (28 bits) and MA-S (36 bits) — for vendors with lower device volumes. This tool primarily queries MA-L (24 bits) in its initial snapshot.
- Why does a MAC sometimes show no vendor?
- Three common reasons. (1) The address is locally administered (LAA): assigned by an operating system or piece of software, not a vendor — modern iPhones, laptops, virtual machines and tunnels do this. (2) The OUI exists at IEEE but is not in the curated snapshot embedded here; the full listing contains over 36,000 entries and this MVP covers the most common vendors. (3) It is a recent assignment registered after the snapshot was taken.
- What does locally administered (LAA) mean?
- The U/L bit in the first octet is set. Global addresses are guaranteed unique by their manufacturer; LAA addresses are invented by the administrator (software, OS, hypervisor) without coordinating with IEEE. Modern mobile platforms use them to prevent cross-network Wi-Fi tracking. If you see an LAA, do not expect a real vendor to show up.
- What does multicast mean?
- The I/G bit in the first octet is set. The address does not represent a single host but a group of receivers. Typical ranges: 01:00:5E:* (IPv4 multicast mapping), 33:33:* (IPv6 multicast), 01:80:C2:* (STP/LACP), 00:00:5E:00:01:* (VRRP). A multicast address is never assigned to a single NIC.
- Is the MAC sent to a server?
- No. All the logic runs in your browser against a snapshot of the IEEE registry embedded in the page at load time. We do not upload the MAC, we do not store it in localStorage and we do not forward it to third parties. You can use the tool with production addresses safely.
- Where does the dataset come from?
- From the public IEEE OUI listing (https://standards-oui.ieee.org/oui/oui.csv). The snapshot embedded in this page is a curated subset of the most common vendors found in logs, networking books and ordinary environments (Cisco, VMware, Apple, Espressif, Raspberry Pi, Huawei, Ubiquiti, etc.). To refresh it from the official source, run `npm run build:oui`, which generates a comparison report.