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)

01a08fb5-68d5-7f7d-89b6-a504d2973d32
01a08fb5-68d6-7138-a322-84baa412af75
01a08fb5-68d6-7273-8790-d01409768449
01a08fb5-68d6-7392-9d18-2ede08fdb65a
01a08fb5-68d6-74a8-9b37-43737fe0ec15
01a08fb5-68d6-75bb-8ddd-3d291ba8f474
01a08fb5-68d6-76d1-8a84-53ad873923b5
01a08fb5-68d6-77e4-9029-7b58f714d5e8
01a08fb5-68d6-78fa-8da6-a4f3cb9cf37e
01a08fb5-68d6-7a11-9d86-a8e2ba14ac6e
01a08fb5-68d6-7b27-925b-c3cdb4be198e
01a08fb5-68d6-7c3e-878e-fef3f5e491d2
01a08fb5-68d6-7d50-8a41-e13b877cbd70
01a08fb5-68d6-7e67-bb59-ec68f96a0a84
01a08fb5-68d6-7f79-bf25-bb8ad1dac429

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)

1f1adbfb-1d09-6348-bf03-4cf95d479851
1f1adbfb-1d09-6528-bf03-4cf95d479851
1f1adbfb-1d09-660e-bf03-4cf95d479851
1f1adbfb-1d09-66d6-bf03-4cf95d479851
1f1adbfb-1d09-679e-bf03-4cf95d479851
1f1adbfb-1d09-6866-bf03-4cf95d479851
1f1adbfb-1d09-692e-bf03-4cf95d479851
1f1adbfb-1d09-6a00-bf03-4cf95d479851
1f1adbfb-1d09-6ac8-bf03-4cf95d479851
1f1adbfb-1d09-6b86-bf03-4cf95d479851
1f1adbfb-1d09-6ce4-bf03-4cf95d479851
1f1adbfb-1d09-6dc0-bf03-4cf95d479851
1f1adbfb-1d09-6e7e-bf03-4cf95d479851
1f1adbfb-1d09-6f3c-bf03-4cf95d479851
1f1adbfb-1d09-6ffa-bf03-4cf95d479851

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)

b1d0a0e0-adbf-11f1-bf03-4cf95d479851
b1d0a14e-adbf-11f1-bf03-4cf95d479851
b1d0a1bc-adbf-11f1-bf03-4cf95d479851
b1d0a22a-adbf-11f1-bf03-4cf95d479851
b1d0a28e-adbf-11f1-bf03-4cf95d479851
b1d0a2fc-adbf-11f1-bf03-4cf95d479851
b1d0a36a-adbf-11f1-bf03-4cf95d479851
b1d0a3ce-adbf-11f1-bf03-4cf95d479851
b1d0a43c-adbf-11f1-bf03-4cf95d479851
b1d0a496-adbf-11f1-bf03-4cf95d479851
b1d0a4fa-adbf-11f1-bf03-4cf95d479851
b1d0a568-adbf-11f1-bf03-4cf95d479851
b1d0a5cc-adbf-11f1-bf03-4cf95d479851
b1d0a626-adbf-11f1-bf03-4cf95d479851
b1d0a68a-adbf-11f1-bf03-4cf95d479851

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)

a8cde02d-2002-8e0f-87ea-5ce32bd83b97
2dc2e12d-2002-8e0f-87ea-5ce32bd83b97
ca0ee22d-2002-8e0f-87ea-5ce32bd83b97
6e11e32d-2002-8e0f-87ea-5ce32bd83b97
15aee52d-2002-8e0f-87ea-5ce32bd83b97
05dde62d-2002-8e0f-87ea-5ce32bd83b97
410ce72d-2002-8e0f-87ea-5ce32bd83b97
983de82d-2002-8e0f-87ea-5ce32bd83b97
a855e92d-2002-8e0f-87ea-5ce32bd83b97
710dea2d-2002-8e0f-87ea-5ce32bd83b97
ae72eb2d-2002-8e0f-87ea-5ce32bd83b97
d154ec2d-2002-8e0f-87ea-5ce32bd83b97
fd2eed2d-2002-8e0f-87ea-5ce32bd83b97
6f1fee2d-2002-8e0f-87ea-5ce32bd83b97
2a7aef2d-2002-8e0f-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)

e79c7e81-f2ae-443a-a538-8236d36d8d71
4b5451f4-4856-4b4e-8346-22300ee7c403
d9d09afb-b1ca-4c10-bf52-1ea73ef5e4d8
fcca13e6-00cb-4d75-8cda-379b9bc1ec78
325d860f-0df9-47c5-a772-def551b84373
c29aea19-6ab1-41fa-9a21-6923c379280a
bdebbde6-f389-4566-8ef9-f82983966820
d5b0a97d-ddfb-457b-8432-b0e607cd1d1d
579023d9-2d63-403b-827d-f690a2d35155
58c0be99-be4d-461b-9afb-bdbe7467feda
0c4984d5-e9a2-4797-a958-b4d22c6fb522
ae79faba-ab80-43bc-b637-cf65318d7146
0176b0c2-67e3-444b-b3f3-8cf344ab40c0
6dfba511-3d85-49bd-acc9-53a29b6dfd3c
f6ca994a-c931-4c8f-8f54-764c26b824d6

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: