UUID & MAC Utils by Daniel Marschall

View the source code

Overview

• Generate time-based UUIDs
  • New: Generate Unix Epoch time-based (version 7) UUID
  • New: Generate reordered Gregorian time-based (version 6) UUID
  • Generate Gregorian time-based (version 1) UUID
  • New: Generate SQL Server sortable time-based (version 8) UUID
• Generate random UUIDs
  • Generate random (version 4) UUID
• Generate other UUID types
  • NCS (variant 0) UUID
  • Generate DCE Security (version 2) UUID
  • Generate name-based (version 3 / 5 / New: 8) UUID
  • New: Generate Custom (version 8) UUID
• Interpret a UUID
• Interpret a MAC address (MAC / EUI / ELI / SAI / AAI)
  • Generate an AAI

Generate random and/or time-based UUIDs

New: Generate Unix Epoch time-based (version 7) UUID ⭐

A UUIDv7 measures time in the Unix Epoch with an accuracy between 1ms and 245ns, depending on how many bits are spent for the timestamp (48-60 bits). The rest of the UUID (62-74 bits) is filled with random data. The timestamp is at the front of the UUID, therefore the UUIDs are monotonically increasing, which is good for using them in database indexes. Since this UUID version does not contain a MAC address, it is also recommended due to the improved privacy.

Show format

Variant 1, Version 7 UUID:
- 48 bit Unix Time in milliseconds
-  4 bit Version (fix 0x7)
- 12 bit Data
-  2 bit Variant (fix 0b10)
- 62 bit Data

Structure of data (74 bits):
- OPTIONAL : Sub-millisecond timestamp fraction (0-12 bits)
- OPTIONAL : Carefully seeded counter
- Random generated bits for any remaining space

Time resolution for various sub-millisecond bits:
0 bits fraction = 1 ms
1 bits fraction = 500 µs
2 bits fraction = 250 µs
3 bits fraction = 125 µs
4 bits fraction = 62.5 µs
5 bits fraction = 31.25 µs
6 bits fraction = 15.625 µs
7 bits fraction = 7.8125 µs
8 bits fraction = 3.90625 µs
9 bits fraction = 1.953125 µs
10 bits fraction = 976.5625 ns
11 bits fraction = 488.28125 ns
12 bits fraction = 244.140625 ns

This implementation outputs:
- 12 bits sub-millisecond timestamp (~245ns resolution)
- no counter
- 62 bits random data

Here are 15 UUIDs that were created just for you! (Reload the page to get more)

01a14f41-c74d-7bbf-82df-4ee0b85e4720
01a14f41-c74d-7d65-aba3-42faba254fbf
01a14f41-c74d-7ea0-8f5f-c17dadb412e5
01a14f41-c74d-7fbb-9e3d-18510775409b
01a14f41-c74e-70d1-b36d-7dd755cc08b5
01a14f41-c74e-71e8-bb11-bfcea07f4362
01a14f41-c74e-72fe-b691-f63e10f7cc9f
01a14f41-c74e-7411-9cf9-f1a5dff602f7
01a14f41-c74e-7527-a1d9-e34e5ad653b2
01a14f41-c74e-763e-b5fc-aea3419eac44
01a14f41-c74e-7754-bb8a-40b801d040f7
01a14f41-c74e-7867-9a02-49ae9ad48c3b
01a14f41-c74e-797d-9653-5c2818da8190
01a14f41-c74e-7a90-92f1-1e85258eb07b
01a14f41-c74e-7ba6-b7bc-098c3b7f4540

New: Generate reordered Gregorian time-based (version 6) UUID ⏰

Like UUIDv1, this kind of UUID is made of the MAC address of the generating computer, the time, and a clock sequence. However, the components in UUIDv6 are reordered (time is at the beginning), so that UUIDs are monotonically increasing, which is good for using them in database indexes.

Show format

Variant 1, Version 6 UUID:
- 48 bit High Time
-  4 bit Version (fix 0x6)
- 12 bit Low Time
-  2 bit Variant (fix 0b10)
-  6 bit Clock Sequence High
-  8 bit Clock Sequence Low
- 48 bit MAC Address

Here are 15 UUIDs that were created just for you! (Reload the page to get more)

1f1cafa0-cfab-6742-a21b-4cf95d479851
1f1cafa0-cfab-68dc-a21b-4cf95d479851
1f1cafa0-cfab-69c2-a21b-4cf95d479851
1f1cafa0-cfab-6a8a-a21b-4cf95d479851
1f1cafa0-cfab-6b5c-a21b-4cf95d479851
1f1cafa0-cfab-6c24-a21b-4cf95d479851
1f1cafa0-cfab-6cec-a21b-4cf95d479851
1f1cafa0-cfab-6db4-a21b-4cf95d479851
1f1cafa0-cfab-6e7c-a21b-4cf95d479851
1f1cafa0-cfab-6f44-a21b-4cf95d479851
1f1cafa0-cfac-608e-a21b-4cf95d479851
1f1cafa0-cfac-616a-a21b-4cf95d479851
1f1cafa0-cfac-6232-a21b-4cf95d479851
1f1cafa0-cfac-62f0-a21b-4cf95d479851
1f1cafa0-cfac-63ae-a21b-4cf95d479851

Generate Gregorian time-based (version 1) UUID ⏰

A UUIDv1 is made of the MAC address of the generating computer, the time, and a clock sequence.

Show format

Variant 1, Version 1 UUID:
- 32 bit Low Time
- 16 bit Mid Time
-  4 bit Version (fix 0x1)
- 12 bit High Time
-  2 bit Variant (fix 0b10)
-  6 bit Clock Sequence High
-  8 bit Clock Sequence Low
- 48 bit MAC Address

Here are 15 UUIDs that were created just for you! (Reload the page to get more)

0cfac480-cafa-11f1-a21b-4cf95d479851
0cfac4e4-cafa-11f1-a21b-4cf95d479851
0cfac548-cafa-11f1-a21b-4cf95d479851
0cfac5ac-cafa-11f1-a21b-4cf95d479851
0cfac606-cafa-11f1-a21b-4cf95d479851
0cfac66a-cafa-11f1-a21b-4cf95d479851
0cfac6c4-cafa-11f1-a21b-4cf95d479851
0cfac728-cafa-11f1-a21b-4cf95d479851
0cfac782-cafa-11f1-a21b-4cf95d479851
0cfac7dc-cafa-11f1-a21b-4cf95d479851
0cfac840-cafa-11f1-a21b-4cf95d479851
0cfac8a4-cafa-11f1-a21b-4cf95d479851
0cfac8fe-cafa-11f1-a21b-4cf95d479851
0cfac962-cafa-11f1-a21b-4cf95d479851
0cfac9bc-cafa-11f1-a21b-4cf95d479851

Generate SQL Server sortable time-based (version 8) UUID

The sorting of UUIDs in SQL Server is rather confusing and incompatible with UUIDv6 and UUIDv7.
Therefore this method developed by HickelSOFT generates UUIDs which are sortable by SQL Server.
They have a time resolution of 1 milliseconds combined with 16 bits of random data.
C# implementation | PHP implementation

Show format

Version 3: Resolution of 1 milliseconds, random part of 16 bits, UTC time, 48 bit random "signature", UUIDv8 compliant:
- 16 bit Random data
-  8 bit UTC Milliseconds transformed from 1000ms to 0..255, deviation -2ms..2ms (hex encoded)
-  8 bit UTC Seconds (hex encoded)
- 16 bit UTC Minute of the day (1..1440, hex encoded) LITTLE ENDIAN (CD AB = 0xABCD)
-  4 bit UUID version 8
- 12 bit UTC Day of the year (1..366, hex encoded) LITTLE ENDIAN (8C AB = 0xABC, whereas 8 is the version)
-  2 bit UUID Variant (0b10)
-  2 bit Unused (must be zero)
- 12 bit UTC Year (hex encoded) BIG ENDIAN
- 48 bit Signature 0x5ce32bd83b97

Version 2: Resolution of 1 milliseconds, random part of 16 bits, UTC time, 48 bit random "signature", UUIDv8 compliant:
- 16 bit Random data
-  8 bit UTC Milliseconds transformed from 1000ms to 0..255, deviation -2ms..2ms (hex encoded)
-  8 bit UTC Seconds (hex encoded)
- 16 bit UTC Minute of the day (1..1440, hex encoded) BIG ENDIAN (AB CD = 0xABCD) = WRONG!!!
-  4 bit UUID version 8
- 12 bit UTC Day of the year (1..366, hex encoded) BIG ENDIAN (8A BC = 0xABC, whereas 8 is the version) = WRONG!!!
-  2 bit UUID Variant (0b10)
-  2 bit Unused (must be zero)
- 12 bit UTC Year (hex encoded) BIG ENDIAN
- 48 bit Signature 0x5ce32bd83b96

Version 1: Resolution of 1 milliseconds, random part of 16 bits, local timezone, 48 zero bits "signature", *NOT* UUIDv8 compliant:
- 16 bit Random data
-  8 bit Generator's local timezone Milliseconds transformed from 1000ms to 0..255, deviation -4ms..0ms (hex encoded)
-  8 bit Generator's local timezone Seconds (BCD encoded)
-  8 bit Generator's local timezone Minute (BCD encoded)
-  8 bit Generator's local timezone Hour (BCD encoded)
-  8 bit Generator's local timezone Day (BCD encoded)
-  8 bit Generator's local timezone Month (BCD encoded)
-  8 bit Generator's local timezone 2-digit year (BCD encoded)
-  8 bit Generator's local timezone 2-digit century (BCD encoded)
- 48 bit Signature 0x000000000000

Here are 15 UUIDs that were created just for you! (Reload the page to get more)

26355c21-3903-8312-87ea-5ce32bd83b97
dd655d21-3903-8312-87ea-5ce32bd83b97
16d85e21-3903-8312-87ea-5ce32bd83b97
0e8a5f21-3903-8312-87ea-5ce32bd83b97
952b6021-3903-8312-87ea-5ce32bd83b97
39d46121-3903-8312-87ea-5ce32bd83b97
3d7d6221-3903-8312-87ea-5ce32bd83b97
41d56321-3903-8312-87ea-5ce32bd83b97
6ac26421-3903-8312-87ea-5ce32bd83b97
bb8b6521-3903-8312-87ea-5ce32bd83b97
54d06621-3903-8312-87ea-5ce32bd83b97
3a436721-3903-8312-87ea-5ce32bd83b97
68d86821-3903-8312-87ea-5ce32bd83b97
a0b16921-3903-8312-87ea-5ce32bd83b97
e75d6a21-3903-8312-87ea-5ce32bd83b97

Generate random (version 4) UUID 🎲

A UUIDv4 is made of 122 random bits. No other information is encoded in this kind of UUID.

Show format

Variant 1, Version 4 UUID:
- 48 bit Random High
-  4 bit Version (fix 0x4)
- 12 bit Random Mid
-  2 bit Variant (fix 0b10)
- 62 bit Random Low

Here are 15 UUIDs that were created just for you! (Reload the page to get more)

101061da-2c6d-44b6-ac57-a2dafb866fbc
9a67286b-6f39-42c9-892d-8673242a95af
0c7a797a-a322-45f8-a604-a828027933ce
1e13d5ea-b876-43e7-b071-8b44edde175f
f89ccdf7-9092-45cb-9524-a959e473d1b8
6adff03f-04c2-438c-bb87-018575caa1ee
c88559b6-6799-4d1b-bd71-4f2e4a72b462
33c66c6a-ee75-4a09-933b-069487ae2df7
87daa339-2890-4dd0-b910-db378e2add58
57b11c82-ba57-40a9-b665-be68a8d8aab4
016fd26b-1abc-4fea-94b5-13da579113d3
81e4dfa2-b7f0-4995-b41f-9e7bdfb81966
b2b9b6b1-1676-4cf8-8d2a-146b9b25eb21
2b02d31a-fed9-45b9-9c50-89a74018d950
7eaa5b24-ce5d-49e1-aa27-f14c03669283

Generate other UUID types

The following types of UUIDs are less common and/or require special knowledge. Please only use the following generators if you know what you are doing.

NCS (variant 0) UUID

The NCS UUIDs are a legacy format initially designed by Apollo Computer that cannot be generated anymore, because the amount of available timestamp bits was exhausted on 5 September 2015. As an example, here is the last possible NCS UUID (all bits of the timestamp are set to 1) for IP address 127.0.0.1: ffffffff-ffff-0000-027f-000001000000.

Show format

Variant 0 UUID:
- 32 bit High Time
- 16 bit Low Time
- 16 bit Reserved
-  1 bit Variant (fix 0b0)
-  7 bit Family
- 56 bit Node

Generate DCE Security (version 2) UUID

A UUIDv2 contains information about the creator (person, group, or organization), the generating system (MAC address), and time. The creator information replaced parts of the time bits, therefore the time resolution is very low.

Show format

Variant 1, Version 2 UUID:
- 32 bit Local Domain Number
- 16 bit Mid Time
-  4 bit Version (fix 0x2)
- 12 bit High Time
-  2 bit Variant (fix 0b10)
-  6 bit Clock Sequence
-  8 bit Local Domain
- 48 bit MAC Address

Generate name-based (version 3 / 5 / New: 8) UUID

A UUIDv3 is made out of a MD5 hash and a UUIDv5 is made out of a SHA1 hash. RFC 9562 also contains an example for a custom UUIDv8 implementation that uses modern hash algorithms.

Show format

Variant 1, Version 3/5/8 UUID:
- 48 bit Hash High
-  4 bit Version (fix 0x3, 0x5, or 0x8)
- 12 bit Hash Mid
-  2 bit Variant (fix 0b10)
- 62 bit Hash Low


As shown in RFC 9562 Appendix B.2:
UUIDv8(HashAlgo, NameSpaceUuid, Data) := ConvertRawBytesToUuid_v8(HashAlgo( Binary[NameSpaceUuid] || Data )).

New: Generate Custom (version 8) UUID

UUIDv8 is made of 122 bits application-specific / custom data. The other 6 bits are used to specify the variant and version of the UUID, to make it RFC-compatible.

Show format

Variant 1, Version 8 UUID:
- 48 bit Custom data [Block 1+2]
-  4 bit Version (fix 0x8)
- 12 bit Custom data [Block 3]
-  2 bit Variant (fix 0b10)
- 62 bit Custom data [Block 4+5]

Interpret a UUID

You can enter a UUID in the following notations:

• Classic notation (case insensitive, curly braces optional): 9e83839a-5967-11e4-8c1c-78e3b5fc7f22
• As OID: 2.25.210700883446948645633376489934419689250

The script will output:

• Notation as UUID and OID
• Version, variant, and additional data (date and time, clock sequence, node id, etc.)

Please enter a UUID or UUID OID:

Interpret a MAC address (MAC / EUI / ELI / SAI / AAI)

You can enter a UUID in the following notations:

• AA-BB-CC-DD-EE-FF
• AA:BB:CC:DD:EE:FF
• AABBCC.DDEEFF (case insensitive)
• AA-BB-CC-DD-EE-FF-11-22 (EUI-64)
• AA:BB:CC:DD:EE:FF-11-22 (EUI-64)
• fe80::1322:33ff:fe44:5566 (IPv6 Link Local / EUI-64)

The script will output:

• Information about the I/G and U/L flags.
• Information about the entry in the IEEE registry, if available.
• Information about the registrant, if available.

Please enter a MAC (EUI, ELI, SAI, AAI), or IPv6-Link-Local address:

Generate an AAI

An Administratively Assigned Identifier (AAI) is a MAC address which can be locally defined by applications or an administrator. Unlike the EUI, an AAI is NOT worldwide unique.

The following options are rather unusual, but are implemented for the sake of completeness: