UUID & MAC Utils by Daniel Marschall

View the source code

Overview

• Generate random and/or time-based UUIDs
  • New: Generate Unix Epoch time-based (version 7) UUID
  • New: Generate reordered Gregorian time-based (version 6) UUID
  • Generate random (version 4) UUID
  • Generate Gregorian time-based (version 1) UUID
  • New: Generate SQL Server sortable time-based (version 8) 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)

019c0e7a-98fc-70b1-a82e-640a37ea3cd3
019c0e7a-98fc-7288-bd33-2ed514314fb3
019c0e7a-98fc-7400-827a-42b3d129837b
019c0e7a-98fc-7550-8a7f-5d452f7b8b50
019c0e7a-98fc-76a0-86bb-938ba809bdbe
019c0e7a-98fc-77e8-aff8-adbd9941fcf2
019c0e7a-98fc-7930-9c57-9a000dda22ee
019c0e7a-98fc-7a77-a806-4ff1bd523d7f
019c0e7a-98fc-7bc3-a8b8-7eda6be0533d
019c0e7a-98fc-7d0f-be97-9bd3160ff270
019c0e7a-98fc-7e57-b525-15a7bb1aee76
019c0e7a-98fc-7f9e-8eba-7bf59f4f2fa3
019c0e7a-98fd-70e6-9d8c-a6c1a796a269
019c0e7a-98fd-7229-916e-c3437cb95d73
019c0e7a-98fd-7371-959e-3e46e8a66810

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)

1f0fdc7a-8796-680e-838b-4cf95d479851
1f0fdc7a-8796-6a52-838b-4cf95d479851
1f0fdc7a-8796-6be2-838b-4cf95d479851
1f0fdc7a-8796-6d4a-838b-4cf95d479851
1f0fdc7a-8796-6e9e-838b-4cf95d479851
1f0fdc7a-8796-6ff2-838b-4cf95d479851
1f0fdc7a-8797-613c-838b-4cf95d479851
1f0fdc7a-8797-62a4-838b-4cf95d479851
1f0fdc7a-8797-6402-838b-4cf95d479851
1f0fdc7a-8797-6556-838b-4cf95d479851
1f0fdc7a-8797-674a-838b-4cf95d479851
1f0fdc7a-8797-689e-838b-4cf95d479851
1f0fdc7a-8797-69e8-838b-4cf95d479851
1f0fdc7a-8797-6b3c-838b-4cf95d479851
1f0fdc7a-8797-6c90-838b-4cf95d479851

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)

fcc97398-fd94-4750-85e2-192315caf6ea
4708b22a-4edb-460e-8b42-e99d4195a2fe
a55a1d1d-e8e1-48c2-85b1-25c530ce9744
98ccd16a-522d-4f00-b3a5-0dff6f88122b
57846306-38d0-4369-949a-1c9514e512ae
1b716392-1593-4cc9-9716-c1481207b9cd
4e8f46c3-ef8d-4006-86ba-f0d82f24c036
ce0e05be-bc8a-48df-913a-0d28112da23e
86322c41-37cf-4386-97a7-10cd639411e1
d70bf35c-6d87-4ba4-bad2-9b336dab96a1
1ff8206f-e7d1-409f-bca2-8c776fd5eab1
07006ba6-68e9-478c-98b1-577297c7cc81
7af87e74-3d4b-4012-a62b-dcb6d2a867b8
883ba050-41f2-4352-9759-1914376df0df
553e5eb5-264a-4edf-831e-c78a13e2abc1

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)

a8798398-fdc7-11f0-838b-4cf95d479851
a879842e-fdc7-11f0-838b-4cf95d479851
a87984ce-fdc7-11f0-838b-4cf95d479851
a879856e-fdc7-11f0-838b-4cf95d479851
a8798604-fdc7-11f0-838b-4cf95d479851
a879869a-fdc7-11f0-838b-4cf95d479851
a8798730-fdc7-11f0-838b-4cf95d479851
a87987c6-fdc7-11f0-838b-4cf95d479851
a8798866-fdc7-11f0-838b-4cf95d479851
a8798906-fdc7-11f0-838b-4cf95d479851
a879899c-fdc7-11f0-838b-4cf95d479851
a8798a32-fdc7-11f0-838b-4cf95d479851
a8798ac8-fdc7-11f0-838b-4cf95d479851
a8798b5e-fdc7-11f0-838b-4cf95d479851
a8798bf4-fdc7-11f0-838b-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)
-  2 bit UUID Variant (0b10)
-  2 bit Unused (must be zero)
- 12 bit UTC Year (hex encoded)
- 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) = WRONG!!!
-  2 bit UUID Variant (0b10)
-  2 bit Unused (must be zero)
- 12 bit UTC Year (hex encoded)
- 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)

c3be8815-7e02-8e01-87ea-5ce32bd83b97
c38d8915-7e02-8e01-87ea-5ce32bd83b97
ea038a15-7e02-8e01-87ea-5ce32bd83b97
73208b15-7e02-8e01-87ea-5ce32bd83b97
06958c15-7e02-8e01-87ea-5ce32bd83b97
b6298d15-7e02-8e01-87ea-5ce32bd83b97
b4ee8e15-7e02-8e01-87ea-5ce32bd83b97
505a9015-7e02-8e01-87ea-5ce32bd83b97
5cb19115-7e02-8e01-87ea-5ce32bd83b97
479c9215-7e02-8e01-87ea-5ce32bd83b97
21ae9315-7e02-8e01-87ea-5ce32bd83b97
c6f79415-7e02-8e01-87ea-5ce32bd83b97
49059515-7e02-8e01-87ea-5ce32bd83b97
d5159615-7e02-8e01-87ea-5ce32bd83b97
cf2c9715-7e02-8e01-87ea-5ce32bd83b97

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: