Generated locally with crypto.getRandomValues - never transmitted.
What it does
Generates random EUI-48 MAC addresses in your browser - one or a batch of up to 100. The tool generates on load and on every option change; Generate re-rolls the batch. Options sit in the left panel, the live list in a sticky right column with a count badge, copy, and a mac-addresses.txt download. Randomness comes from crypto.getRandomValues locally - nothing is transmitted. Every option is encoded in the URL, so a format you dialed in can be bookmarked or shared as a link.
How to use it
- Pick a format - the separator control, or one of the quick-pick chips:
| Preset | Shape | Where you see it |
|---|---|---|
| Colon, lowercase (default) | 02:9f:1a:c4:b7:e8 |
Linux ip link, macOS ifconfig |
| Dash, uppercase | 02-9F-1A-C4-B7-E8 |
Windows ipconfig /all, getmac |
| Dot, lowercase | 02.9f.1a.c4.b7.e8 |
dotted octet pairs some switch CLIs print |
| No separator | 029f1ac4b7e8 |
bare hex for configs, filters, and regexes |
- Optionally enter a 6-hex-digit OUI prefix such as
aabbcc. Separators inside it are tolerated (aa-bb-ccworks). - Set Count (1-100), toggle Uppercase or Locally administered as needed, and press Generate to re-roll.
- Copy the list, download it as
mac-addresses.txt, or share the URL - it carries your options (?sep=-&case=upper&n=10).
Examples
The deterministic examples below were produced with a fixed test sequence (octets 02 9f 1a c4 b7 e8), so they are exact:
- Locally administered, colon (the default):
02:9f:1a:c4:b7:e8 - Dash separator:
02-9f-1a-c4-b7-e8- same address, different shape - Dotted:
02.9f.1a.c4.b7.e8 - Bare:
029f1ac4b7e8 - Uppercase:
02:9F:1A:C4:B7:E8- display only; the address is identical - OUI
aabbccpinned:aa:bb:cc:02:9f:1a- your three octets, random rest - OUI
001132with Locally administered on:02:11:32:02:9f:1a- the U/L bit is forced onto the vendor’s first octet - The same OUI with it off:
00:11:32:02:9f:1a - Malformed OUI (
zz): showsInvalid OUI: OUI must be 6 hex digits, got "zz"and generates nothing - A real run with the crypto RNG:
33:89:a4:f0:90:b6- note the odd first octet (see below)
Good to know
A MAC address is 48 bits - six octets. The first three form the OUI (the vendor half, assigned by the IEEE); the last three are the device half. Two flag bits live in the first octet:
| Bit | Mask | Name | When set |
|---|---|---|---|
| least significant | 0x01 |
multicast | targets a group, not one interface |
| second-least significant | 0x02 |
U/L | locally administered, not vendor-assigned |
- Why locally administered is the default. A universal address belongs to real hardware; test data using real vendor OUIs can collide with machines on your network. Forcing the U/L bit marks the address as locally assigned - you keep the format, drop the vendor claim, and stop impersonating hardware.
02:9f:1a:c4:b7:e8is exactly that: first octet02= U/L set, unicast. - The U/L flag only touches the
0x02bit. The multicast bit (0x01) is left alone, so a run can produce an odd first octet such as33:89:…. Fine for test data and documentation; filter for an even first octet if you need guaranteed unicast. - Uppercase is display only -
02:9f:1aand02:9F:1Aare the same address. - Options live in the URL (
sep,case=upper,oui,la=0,n); the generated values themselves do not - a shared link re-rolls fresh addresses for the recipient. - Count caps at 100 per batch; press Generate again for more.
- Private: randomness comes from
crypto.getRandomValueslocally - never transmitted. - Related tools: Random Port Generator,
UUIDUUIDA 128-bit identifier generated to be practically unique without coordination, most commonly in version-4 (fully random) form.
Generator.