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)

019f91af-fe36-7186-b157-b82939d4e6ab
019f91af-fe36-7348-8d2d-34b035a203d3
019f91af-fe36-7498-bc6f-f2494f94a91e
019f91af-fe36-75bf-9186-349075d4652c
019f91af-fe36-76e2-8550-d49f9b43d482
019f91af-fe36-77f8-a975-9450c8a3a420
019f91af-fe36-791b-81a3-3b280041af56
019f91af-fe36-7a3e-95d6-bcc0e303e40e
019f91af-fe36-7b5d-be45-8b7018ffcc0a
019f91af-fe36-7c84-bc89-6b9571d065a1
019f91af-fe36-7da2-8593-1e0b173213f2
019f91af-fe36-7ec1-8341-5470cf08d0a9
019f91af-fe36-7fe0-9b03-6439be3680e6
019f91af-fe37-7103-887e-ee18f3a42f4e
019f91af-fe37-7225-a196-4918718ab4cb

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)

1f186fcf-e3b8-6f88-8713-4cf95d479851
1f186fcf-e3b9-6168-8713-4cf95d479851
1f186fcf-e3b9-6258-8713-4cf95d479851
1f186fcf-e3b9-633e-8713-4cf95d479851
1f186fcf-e3b9-641a-8713-4cf95d479851
1f186fcf-e3b9-64f6-8713-4cf95d479851
1f186fcf-e3b9-65be-8713-4cf95d479851
1f186fcf-e3b9-6690-8713-4cf95d479851
1f186fcf-e3b9-6762-8713-4cf95d479851
1f186fcf-e3b9-6834-8713-4cf95d479851
1f186fcf-e3b9-69a6-8713-4cf95d479851
1f186fcf-e3b9-6a82-8713-4cf95d479851
1f186fcf-e3b9-6b4a-8713-4cf95d479851
1f186fcf-e3b9-6c12-8713-4cf95d479851
1f186fcf-e3b9-6cda-8713-4cf95d479851

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)

fe3b9dc0-86fc-11f1-8713-4cf95d479851
fe3b9e2e-86fc-11f1-8713-4cf95d479851
fe3b9e9c-86fc-11f1-8713-4cf95d479851
fe3b9f0a-86fc-11f1-8713-4cf95d479851
fe3b9f78-86fc-11f1-8713-4cf95d479851
fe3b9fdc-86fc-11f1-8713-4cf95d479851
fe3ba04a-86fc-11f1-8713-4cf95d479851
fe3ba0a4-86fc-11f1-8713-4cf95d479851
fe3ba112-86fc-11f1-8713-4cf95d479851
fe3ba176-86fc-11f1-8713-4cf95d479851
fe3ba1e4-86fc-11f1-8713-4cf95d479851
fe3ba23e-86fc-11f1-8713-4cf95d479851
fe3ba2a2-86fc-11f1-8713-4cf95d479851
fe3ba306-86fc-11f1-8713-4cf95d479851
fe3ba36a-86fc-11f1-8713-4cf95d479851

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)

09940a12-4b00-8d0c-87ea-5ce32bd83b97
519d0b12-4b00-8d0c-87ea-5ce32bd83b97
0aac0c12-4b00-8d0c-87ea-5ce32bd83b97
0c4d0d12-4b00-8d0c-87ea-5ce32bd83b97
d4db0e12-4b00-8d0c-87ea-5ce32bd83b97
e85d0f12-4b00-8d0c-87ea-5ce32bd83b97
82761012-4b00-8d0c-87ea-5ce32bd83b97
4c7e1112-4b00-8d0c-87ea-5ce32bd83b97
a2751212-4b00-8d0c-87ea-5ce32bd83b97
cb761312-4b00-8d0c-87ea-5ce32bd83b97
e7181412-4b00-8d0c-87ea-5ce32bd83b97
8fbe1512-4b00-8d0c-87ea-5ce32bd83b97
4a6e1612-4b00-8d0c-87ea-5ce32bd83b97
9fd31712-4b00-8d0c-87ea-5ce32bd83b97
4b091912-4b00-8d0c-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)

cea17269-98eb-4743-b922-4e748915a7b4
5ca58f6a-5094-4da6-9701-96d859e3a5cd
398115aa-da4e-40ff-9fe8-291178ef47bf
f7b20051-6c99-4cf3-9d34-9c06e7e893ec
32b7f434-6abb-46db-91d6-4990fec9b63c
6c1fdd07-9d13-44ca-a8df-04ed85720b94
15601419-75f2-4571-9fc6-82569606adcf
8dc2ab3d-382b-4314-8a10-925fa7a57458
2e375651-aa49-444a-ada7-54d2749dc39c
094ef1ff-288c-40eb-bf79-a4f0ea0084eb
eece1887-ef32-4612-852f-77a33f23aa8b
f2fd9159-9b78-44cb-af02-3243203e2105
73875f6a-6d62-46bc-989f-8365c447c1b7
2ba09948-9cd2-4e4a-8eb5-818970cbc5ac
8a68e9a9-ac47-450f-8ce8-26aa85f32c31

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: