MAC Address Vendor (OUI) Lookup
Decode any MAC address to its manufacturer. Detects randomized/private MACs. Works offline for common vendors.
What a MAC address tells you
Every network interface has a 48-bit MAC address split in two halves. The first 24 bits (OUI — Organizationally Unique Identifier) identify the manufacturer. The IEEE assigns these. The second 24 bits are the per-device serial within that manufacturer.
Example: 00:50:56:AB:CD:EF — the OUI 00:50:56 is registered to VMware, Inc. So this MAC is a VMware virtual NIC.
Why this matters in practice
- DHCP table analysis — looking at your router's DHCP leases and identifying which devices are which.
- Wi-Fi audit — seeing what's connecting (or attempting to connect) to your network.
- Inventory — large networks use OUI lookups to auto-classify devices by vendor.
- Forensics — packet captures contain MACs; OUIs help identify what generated traffic.
Local vs universal MACs
The second-least-significant bit of the first byte indicates if a MAC is locally administered (set by software, e.g. for privacy) or universally administered (assigned by IEEE). If it's set, the OUI isn't an IEEE-registered vendor — common with modern phones and laptops doing MAC randomization.
iPhone, recent Android, Windows 11, and macOS all randomize their Wi-Fi MAC per-network by default. So an unfamiliar OUI on your guest network might just be a phone using a private MAC, not a mysterious device.