MAC Address Generator

Create cryptographically random local MAC addresses, preserve a custom prefix, generate deterministic test fixtures, inspect address bits and formats, derive Modified EUI-64 identifiers, and export unique batches—all without a vendor database or network request.

Secure randomness · local only

Generator controls

Address mode

Optional fixed byte prefix (1–5 bytes)

Deterministic fixture mode (not cryptographically random)

Default mode sets the IEEE local bit and clears the group bit.

Generated address

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A random address with the universal/local bit cleared is only a bit pattern—it is not an IEEE-assigned vendor address. For private randomized use, choose Local + unicast.

MAC inspector

MAC / EUI-48

Ready.

Derived identifiers

Modified EUI-64 interface identifier

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Illustrative IPv6 link-local form

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Unique batch generator

up to 10,000

Count

Output format

Collision estimate will appear here.

Preview

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IEEE bit semantics

The least-significant bit of the first octet is the Individual/Group bit. The next bit is the Universal/Local bit. Random private-device/test addresses should normally be locally administered unicast addresses: I/G = 0 and U/L = 1.

Supplying an OUI-like prefix does not grant rights to use somebody else’s assignment. This tool intentionally does not claim vendor identity from offline or stale OUI data.

EUI-64 caution

The Modified EUI-64 derivation inserts ff:fe and flips the universal/local bit. It is useful for protocol analysis and legacy configuration, but modern IPv6 hosts commonly use privacy/stable interface identifiers instead of exposing a hardware MAC-derived identifier.