Network · Developer
MAC address generator.
Generate random, valid MAC addresses — locally administered so they never collide with a real manufacturer's assigned range. Choose the separator, case, and unicast or multicast, then bulk-create up to 50 at a time.
Options
MAC addresses
Pick options, then press Generate.
How it's generated
A MAC address is 48 bits (6 bytes). This generator randomizes all 6 bytes, then fixes two specific bits in the first byte so the result is always a valid, safely-assignable address:
The I/G bit (least significant bit of the first octet) is 0 for a unicast (single-device) address and 1 for multicast (group) — controlled by the checkbox above. The U/L bit (second-least-significant bit of the first octet) is always set to 1 here, marking the address as locally administered rather than manufacturer-assigned, so it can never collide with a real device's factory-assigned OUI range.
Reference: the MAC address bit conventions this follows (I/G and U/L bit positions) are standard IEEE 802 addressing rules.
Frequently asked questions
Why is the address always "locally administered"?
Real network hardware ships with a universally-administered address, whose first 3 bytes (the OUI) are assigned to a specific manufacturer by the IEEE. Setting the U/L bit marks a generated address as one nobody's factory will ever produce, which is exactly what the bit exists for — safely assigning your own addresses (e.g. to VMs, containers, or test devices) without any chance of colliding with real hardware.
Can I use one of these on a real device?
Many operating systems and hypervisors let you set a custom MAC address on a virtual or physical network interface, and a locally-administered address like these is the correct, standards-compliant choice for that. Two devices on the same network segment still can't share a MAC address, so treat these as random candidates, not guaranteed-unique allocations.
What's the difference between unicast and multicast here?
Unicast (the default) addresses a single network interface. Multicast addresses a group of interfaces that have joined that group — used for things like multicast video streams. Most everyday uses (spoofing a NIC, labelling a test device) want unicast.
Random locally-administered addresses only
Generated entirely in your browser with crypto.getRandomValues — nothing is sent to any server. These are not real device identities, and this tool doesn't look up or spoof any actual hardware vendor's OUI range.