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MAC Address Generator

Generate 1–20 cryptographically random, locally administered unicast 48-bit MAC addresses for safe test data.

Privacy: your files never leave your device. All processing happens locally in your browser.

How to use

  1. 1.Choose how many local test addresses to create and select the output format.
  2. 2.Select Generate local MAC addresses; fresh bytes come from Web Crypto.
  3. 3.Check for collisions in your own allocation system before assigning any generated value.

About MAC Address Generator

MAC Address Generator creates random 48-bit addresses for labs, documentation, fixtures, virtual machines, and software tests. Choose a count from 1 to 20, select colon, hyphen, or plain formatting, and choose uppercase or lowercase hexadecimal. Generation happens locally with the browser's cryptographic random source.

Every result contains six octets. The first octet is modified so its locally administered U/L bit is 1 and its individual/group I/G bit is 0. This produces a local unicast address rather than a multicast address or a value that pretends to use an IEEE-assigned vendor OUI. The other 46 bits remain random.

Eight boundary fixtures pass all possible combinations of the two low bits through the mask while also checking high-bit preservation. The implementation formats exactly two hexadecimal digits per byte and validates the six-byte length, supported separators, count boundary, and case option.

Random generation does not guarantee uniqueness across all time or systems. With a 46-bit local-unicast space, collisions are unlikely for small test sets but still possible. A production network, hypervisor, orchestrator, or device-management system should maintain its own allocation registry and detect duplicates.

Changing a MAC address can disrupt network access, violate organizational policy, trigger security monitoring, or impersonate another device. This page only generates text. It does not modify an interface, bypass access controls, scan a network, look up vendors, or verify that an address is unused.

Use these addresses only in environments you own or are authorized to administer. For hardware manufacture, globally unique assignments, regulated networks, or vendor identification, obtain and follow the appropriate IEEE registration and organizational allocation process.

Methodology & sources

Validate a 1–20 count, obtain six random bytes per result from crypto.getRandomValues, set bit 1 and clear bit 0 of the first octet to create a locally administered individual address, retain all other bits, serialize each byte as two hex digits using the selected separator and case, and perform no device or network operation.

Frequently asked questions

Are these vendor MAC addresses?
No. The locally administered bit is set, so the values do not claim an IEEE vendor OUI.
Are the addresses unicast?
Yes. The multicast I/G bit is cleared in every result.
Are generated addresses guaranteed unique?
No. They are random; production allocation still needs collision detection and a registry.
Does this change my device MAC?
No. The tool only displays text and never accesses network interfaces.

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