Espressif Inc.

Any device whose MAC address begins with B4:BF:E9 has a network interface built by Espressif Inc.. This prefix (the OUI, or Organizationally Unique Identifier) is assigned by the IEEE and is the first three octets of the address.

OUI prefix

B4:BF:E9

Organization

Espressif Inc.

Address

Room 204, Building 2, 690 Bibo Rd, Pudong New Area Shanghai Shanghai CN 201203

Source

IEEE OUI registry

Have a full MAC address? Look it up— we'll also tell you if it's a randomized (private) address rather than a real manufacturer prefix.