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)

01a03d94-fa6b-7396-85d1-ebfe7da3ed2c
01a03d94-fa6b-758a-90c6-4fcf628185a2
01a03d94-fa6b-76bd-af6e-279e0b521cfc
01a03d94-fa6b-77d8-b6e5-db52f83695df
01a03d94-fa6b-78ee-97ad-f1a2e76291b2
01a03d94-fa6b-7a05-8bfd-fc274c00b674
01a03d94-fa6b-7b1f-9072-82aeb4f5fc87
01a03d94-fa6b-7c32-b6fd-201443bd573c
01a03d94-fa6b-7d44-ae21-b8baf0eeb185
01a03d94-fa6b-7e5b-8933-c6ead6242b93
01a03d94-fa6b-7f6d-a7f1-77e89daab52d
01a03d94-fa6c-707f-b3ce-cc6452530da0
01a03d94-fa6c-7196-8f8c-c25d86a8591c
01a03d94-fa6c-72a8-8cc4-1007d7904cb8
01a03d94-fa6c-73bf-80b0-37d451ecf75f

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)

1f1a1379-ef76-6808-9724-4cf95d479851
1f1a1379-ef76-6a06-9724-4cf95d479851
1f1a1379-ef76-6b0a-9724-4cf95d479851
1f1a1379-ef76-6bdc-9724-4cf95d479851
1f1a1379-ef76-6ca4-9724-4cf95d479851
1f1a1379-ef76-6d6c-9724-4cf95d479851
1f1a1379-ef76-6e2a-9724-4cf95d479851
1f1a1379-ef76-6ee8-9724-4cf95d479851
1f1a1379-ef76-6fb0-9724-4cf95d479851
1f1a1379-ef77-606e-9724-4cf95d479851
1f1a1379-ef77-61cc-9724-4cf95d479851
1f1a1379-ef77-62b2-9724-4cf95d479851
1f1a1379-ef77-637a-9724-4cf95d479851
1f1a1379-ef77-6438-9724-4cf95d479851
1f1a1379-ef77-6500-9724-4cf95d479851

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)

9ef775d2-a137-11f1-9724-4cf95d479851
9ef77640-a137-11f1-9724-4cf95d479851
9ef776a4-a137-11f1-9724-4cf95d479851
9ef77708-a137-11f1-9724-4cf95d479851
9ef7776c-a137-11f1-9724-4cf95d479851
9ef777d0-a137-11f1-9724-4cf95d479851
9ef77834-a137-11f1-9724-4cf95d479851
9ef77898-a137-11f1-9724-4cf95d479851
9ef778fc-a137-11f1-9724-4cf95d479851
9ef77960-a137-11f1-9724-4cf95d479851
9ef779c4-a137-11f1-9724-4cf95d479851
9ef77a28-a137-11f1-9724-4cf95d479851
9ef77a8c-a137-11f1-9724-4cf95d479851
9ef77af0-a137-11f1-9724-4cf95d479851
9ef77b5e-a137-11f1-9724-4cf95d479851

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)

732cbf1c-6c02-8e0e-87ea-5ce32bd83b97
95b0c01c-6c02-8e0e-87ea-5ce32bd83b97
2d05c11c-6c02-8e0e-87ea-5ce32bd83b97
a5e6c21c-6c02-8e0e-87ea-5ce32bd83b97
46a8c31c-6c02-8e0e-87ea-5ce32bd83b97
7df5c41c-6c02-8e0e-87ea-5ce32bd83b97
7c2ac51c-6c02-8e0e-87ea-5ce32bd83b97
d0e7c61c-6c02-8e0e-87ea-5ce32bd83b97
836bc71c-6c02-8e0e-87ea-5ce32bd83b97
875cc81c-6c02-8e0e-87ea-5ce32bd83b97
8642c91c-6c02-8e0e-87ea-5ce32bd83b97
d786ca1c-6c02-8e0e-87ea-5ce32bd83b97
d99ccb1c-6c02-8e0e-87ea-5ce32bd83b97
29d5cc1c-6c02-8e0e-87ea-5ce32bd83b97
8f99cd1c-6c02-8e0e-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)

4697533d-f8c8-442e-b970-3af1f706089d
e8b1a1fa-7e49-4159-a2e0-5578830f558e
40527952-d1e6-408f-b1c2-a2ee9d613bdb
2d636bed-9919-4994-8488-e01cfc04d708
17573835-f5d8-4371-a4c8-c4ac90bbf2fb
59c55d78-30ea-44e3-ba26-a86b2fcb1ffc
ac68e7f6-db70-48e7-ba71-a23cddc2d8fa
533fe762-f368-4cee-927b-7f55db161f7e
42baa57a-b80d-4346-b4eb-18e8fc7c35f8
411a3ee1-df34-49f8-b541-825a10a7bd5a
c7208f07-3992-4e82-916c-39c939c4d95a
20d7a323-b354-4ad7-87bc-c5d63942d9aa
45e6b5a8-511c-4e6c-a6e0-300ae03f7122
866b5098-7307-4778-ac6a-61532a14f935
af3bd42f-56ce-44dd-a6ed-663f9be9cf48

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: