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)

019acd6f-541c-78d5-b5c4-3d76d4fae2f7
019acd6f-541c-7a67-ace0-081812f4ec0b
019acd6f-541c-7ba2-bab3-911c6a833efb
019acd6f-541c-7cc1-abb4-0f0f076861e4
019acd6f-541c-7de0-a32e-655ec41779a7
019acd6f-541c-7efa-9c17-134efa577772
019acd6f-541d-7015-a33f-a0bef199efe5
019acd6f-541d-7130-a2a0-4c94a3f6d572
019acd6f-541d-724a-8e7d-cdebc285da16
019acd6f-541d-7361-b09f-f47a7e1cda29
019acd6f-541d-747b-8a1c-0161a6813c81
019acd6f-541d-7596-b1be-20ab316d4a74
019acd6f-541d-76b5-8426-156b8a48a104
019acd6f-541d-77cb-830d-1d87e3359016
019acd6f-541d-78e6-a89c-b54d0f6da219

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)

1f0cccae-0470-6648-8460-4cf95d479851
1f0cccae-0470-67d8-8460-4cf95d479851
1f0cccae-0470-68c8-8460-4cf95d479851
1f0cccae-0470-6990-8460-4cf95d479851
1f0cccae-0470-6a58-8460-4cf95d479851
1f0cccae-0470-6b20-8460-4cf95d479851
1f0cccae-0470-6bde-8460-4cf95d479851
1f0cccae-0470-6ca6-8460-4cf95d479851
1f0cccae-0470-6d6e-8460-4cf95d479851
1f0cccae-0470-6e2c-8460-4cf95d479851
1f0cccae-0470-6f6c-8460-4cf95d479851
1f0cccae-0471-603e-8460-4cf95d479851
1f0cccae-0471-6106-8460-4cf95d479851
1f0cccae-0471-61ce-8460-4cf95d479851
1f0cccae-0471-6296-8460-4cf95d479851

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)

cefeb545-ace5-45c9-bf4b-00dd4b11711a
edefc1aa-c190-4e12-8374-6e4012a5b956
44d3aab2-3dfc-4216-aa01-93d462e7cd5a
21898243-28b0-45c1-af7c-2f62df700318
94cb3d0c-41cc-4e76-ae6f-a17d8aab8d15
a618f2c2-9dd5-47ee-9713-8540f46105f7
cf57261f-8286-4013-9e19-e9fa1050ee25
112445d3-de28-4720-b17d-b7158235e815
7b0f5be0-e6b0-4777-8f7d-991083fcc791
9a1b8b68-93d8-43ec-bb59-54521c6f7b32
530cf9b3-8561-46c5-b737-5afa4e685b94
2c04ff61-160f-4cbf-a10c-2d0a8421fb8f
c2648f37-a130-4df9-bc6a-def0d75aafa9
2d386aee-0036-4477-8bc3-6494bd1dd9b1
86780699-1818-4bd0-bb75-c80cb3827b83

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)

e0471872-ccca-11f0-8460-4cf95d479851
e04718d6-ccca-11f0-8460-4cf95d479851
e047193a-ccca-11f0-8460-4cf95d479851
e047199e-ccca-11f0-8460-4cf95d479851
e0471a02-ccca-11f0-8460-4cf95d479851
e0471a66-ccca-11f0-8460-4cf95d479851
e0471ac0-ccca-11f0-8460-4cf95d479851
e0471b24-ccca-11f0-8460-4cf95d479851
e0471b88-ccca-11f0-8460-4cf95d479851
e0471bf6-ccca-11f0-8460-4cf95d479851
e0471c64-ccca-11f0-8460-4cf95d479851
e0471cc8-ccca-11f0-8460-4cf95d479851
e0471d2c-ccca-11f0-8460-4cf95d479851
e0471d90-ccca-11f0-8460-4cf95d479851
e0471df4-ccca-11f0-8460-4cf95d479851

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)

fd06ab38-9300-8d14-87e9-5ce32bd83b97
ff0cac38-9300-8d14-87e9-5ce32bd83b97
54c8ad38-9300-8d14-87e9-5ce32bd83b97
1b2fae38-9300-8d14-87e9-5ce32bd83b97
6963af38-9300-8d14-87e9-5ce32bd83b97
0bcab038-9300-8d14-87e9-5ce32bd83b97
4d05b138-9300-8d14-87e9-5ce32bd83b97
1b23b238-9300-8d14-87e9-5ce32bd83b97
84efb338-9300-8d14-87e9-5ce32bd83b97
5ac2b438-9300-8d14-87e9-5ce32bd83b97
bae8b538-9300-8d14-87e9-5ce32bd83b97
c942b738-9300-8d14-87e9-5ce32bd83b97
e358b838-9300-8d14-87e9-5ce32bd83b97
fbcfb938-9300-8d14-87e9-5ce32bd83b97
fa4dba38-9300-8d14-87e9-5ce32bd83b97

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

An 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

An UUIDv3 is made out of a MD5 hash and an 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: