Which company owns MAC address prefix E4:65:B8?

MAC address prefix E4:65:B8 is registered to Espressif Inc. in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with E4:65:B8 has a network interface built by Espressif Inc..

What is the OUI E4:65:B8?

E4:65:B8 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Espressif Inc.. It covers every address from E4:65:B8:00:00:00 to E4:65:B8:FF:FF:FF, or 16,777,216 addresses in total. It is also written E4-65-B8.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in E4:65:B8:00:00:00 that is E4:65:B8 — and look that prefix up in the IEEE OUI registry. If the second-lowest bit of the first octet is set, the address is locally administered (a randomized or private MAC), which belongs to no manufacturer and will not resolve; modern phones and laptops use these by default on each network.

Where is Espressif Inc. located?

Espressif Inc. is listed at Room 204, Building 2, 690 Bibo Rd, Pudong New Area Shanghai Shanghai CN 201203 in the IEEE OUI registry entry for E4:65:B8. This is the address the organization registered with the IEEE, which may differ from its current operating address.

How many MAC prefixes does Espressif Inc. own?

Espressif Inc. holds 335 OUI prefixes in the IEEE registry, of which E4:65:B8 is one. A device made by Espressif Inc. could carry a MAC address from any of them.

Espressif Inc.

MAC address prefix E4:65:B8 is registered to Espressif Inc. in the IEEE OUI registry. Any device whose MAC address begins with E4:65:B8 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 — it covers every MAC from E4:65:B8:00:00:00 to E4:65:B8:FF:FF:FF.

OUI prefix: E4:65:B8
Hyphen form: E4-65-B8
MAC range: E4:65:B8:00:00:00 – E4:65:B8:FF:FF:FF
Addresses in block: 16,777,216
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.

Other prefixes from Espressif Inc.

Espressif Inc. holds 335 OUI prefixes in total. A device with this exact prefix could just as well carry any of these:

Assignment history (1)

The IEEE registry publishes current state only — this is the change record we've kept since we started tracking it daily.

2026-07-17Assigned to "Espressif Inc."

Nearby in the registry

The prefixes assigned immediately before and after E4:65:B8:

FAQ

Which company owns MAC address prefix E4:65:B8?: MAC address prefix E4:65:B8 is registered to Espressif Inc. in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with E4:65:B8 has a network interface built by Espressif Inc..
What is the OUI E4:65:B8?: E4:65:B8 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to Espressif Inc.. It covers every address from E4:65:B8:00:00:00 to E4:65:B8:FF:FF:FF, or 16,777,216 addresses in total. It is also written E4-65-B8.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in E4:65:B8:00:00:00 that is E4:65:B8 — and look that prefix up in the IEEE OUI registry. If the second-lowest bit of the first octet is set, the address is locally administered (a randomized or private MAC), which belongs to no manufacturer and will not resolve; modern phones and laptops use these by default on each network.
Where is Espressif Inc. located?: Espressif Inc. is listed at Room 204, Building 2, 690 Bibo Rd, Pudong New Area Shanghai Shanghai CN 201203 in the IEEE OUI registry entry for E4:65:B8. This is the address the organization registered with the IEEE, which may differ from its current operating address.
How many MAC prefixes does Espressif Inc. own?: Espressif Inc. holds 335 OUI prefixes in the IEEE registry, of which E4:65:B8 is one. A device made by Espressif Inc. could carry a MAC address from any of them.