What it does
Every network interface has a MAC address such as 3C:5A:B4:12:34:56. The first 3 bytes (6 hex digits) are the OUI (Organizationally Unique Identifier), assigned by the IEEE to the manufacturer. This tool resolves that prefix to the vendor name, entirely client-side using a bundled lookup table — no data ever leaves your browser.
Try it
How it works
- The input is cleaned of separators (
:,-,., spaces) and upper-cased. - The first 6 hex characters (3 bytes) are extracted — this is the OUI.
- The two low-order bits of the first byte are also inspected to report whether the address is:
- Unicast or Multicast (bit 0 of the first octet)
- Universally Administered (UAA) or Locally Administered (LAA) (bit 1 of the first octet)
- The OUI is looked up in a local table (
data/oui.json) bundled with this tool. If your device isn't recognized, it's likely a newer or less common assignment not in the offline snapshot.
The offline dataset can be refreshed from the official IEEE registry by running npm run fetch-oui in the project (requires internet access), which regenerates data/oui.json from the public IEEE MA-L listing.
Notes
- Locally Administered Addresses (LAA) are often randomly generated by the OS (e.g. iOS/Android MAC randomization for Wi-Fi privacy) and will not map to a real vendor — this is expected and the tool will tell you so.
- This tool works fully offline once the page is loaded.