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)

019d8981-12aa-781d-8ed8-39dc6b19ba6f
019d8981-12aa-7a4a-b959-7a58fa341af5
019d8981-12aa-7baf-a821-aeb95304db1c
019d8981-12aa-7cfa-a3a2-82f464963a89
019d8981-12aa-7e3e-acb9-3c162dba0cc1
019d8981-12aa-7f79-885d-6682d71fa317
019d8981-12ab-70b5-aea6-cb0a2c545434
019d8981-12ab-71f0-95b3-0eea655a652f
019d8981-12ab-731f-bbbe-d5dfdb13bdd4
019d8981-12ab-743e-acce-3f5ec405abaa
019d8981-12ab-7554-92e4-4b9d4b917c73
019d8981-12ab-766b-9ef7-83efa4d92f8c
019d8981-12ab-7786-aa28-ad766544f293
019d8981-12ab-78a0-96c1-a62d15217f2b
019d8981-12ab-79bb-b0e5-286f75d42093

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)

1f1379d5-56a9-63b2-b62d-4cf95d479851
1f1379d5-56a9-6556-b62d-4cf95d479851
1f1379d5-56a9-6646-b62d-4cf95d479851
1f1379d5-56a9-6718-b62d-4cf95d479851
1f1379d5-56a9-67d6-b62d-4cf95d479851
1f1379d5-56a9-689e-b62d-4cf95d479851
1f1379d5-56a9-6966-b62d-4cf95d479851
1f1379d5-56a9-6a24-b62d-4cf95d479851
1f1379d5-56a9-6ae2-b62d-4cf95d479851
1f1379d5-56a9-6ba0-b62d-4cf95d479851
1f1379d5-56a9-6e02-b62d-4cf95d479851
1f1379d5-56a9-6ed4-b62d-4cf95d479851
1f1379d5-56a9-6fa6-b62d-4cf95d479851
1f1379d5-56aa-6064-b62d-4cf95d479851
1f1379d5-56aa-612c-b62d-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)

4627bd47-1045-44ad-8cdd-d166b24301bf
2ced7e4e-aeea-4a8e-bc12-c1678065f95b
45fc884b-fa77-4595-89c4-639c238e0fe1
63de0acd-6c44-4e10-a59c-9a74ba493024
36b7fe75-10fd-4caf-9b78-b76df4e98a33
ef11b2aa-1e26-49b5-81ca-391a4aeac07c
0d66b91f-6e05-4e04-8a06-0d38fbac9639
1ce2bdc7-05be-4826-8b4b-bebb55af8547
f20d05ce-288f-4374-bba4-575ec3d721a7
08621f39-5584-466d-8c60-cef8a56a3328
3d8a0843-93f7-4c09-8a4a-c2e14d501c5b
ce8a9c48-ffb3-44d0-ad1d-62a002e1fd45
c08d455c-7dac-42c6-b6b7-ea65c27fdcea
bff85cac-7c1e-4474-a220-2a4bca490e38
fd0d7702-c9e1-4d0a-9572-e379fdf4cf0f

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)

556aa870-379d-11f1-b62d-4cf95d479851
556aa8fc-379d-11f1-b62d-4cf95d479851
556aa97e-379d-11f1-b62d-4cf95d479851
556aaa0a-379d-11f1-b62d-4cf95d479851
556aaaa0-379d-11f1-b62d-4cf95d479851
556aab40-379d-11f1-b62d-4cf95d479851
556aabd6-379d-11f1-b62d-4cf95d479851
556aac76-379d-11f1-b62d-4cf95d479851
556aad0c-379d-11f1-b62d-4cf95d479851
556aada2-379d-11f1-b62d-4cf95d479851
556aae38-379d-11f1-b62d-4cf95d479851
556aaef6-379d-11f1-b62d-4cf95d479851
556aaf96-379d-11f1-b62d-4cf95d479851
556ab022-379d-11f1-b62d-4cf95d479851
556ab0cc-379d-11f1-b62d-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)

1cc9c31e-3d00-8806-87ea-5ce32bd83b97
0160c41e-3d00-8806-87ea-5ce32bd83b97
e9b4c51e-3d00-8806-87ea-5ce32bd83b97
4905c61e-3d00-8806-87ea-5ce32bd83b97
915ec71e-3d00-8806-87ea-5ce32bd83b97
6b6ec81e-3d00-8806-87ea-5ce32bd83b97
3874c91e-3d00-8806-87ea-5ce32bd83b97
d776ca1e-3d00-8806-87ea-5ce32bd83b97
7677cb1e-3d00-8806-87ea-5ce32bd83b97
1237cc1e-3d00-8806-87ea-5ce32bd83b97
457fcd1e-3d00-8806-87ea-5ce32bd83b97
255ccf1e-3d00-8806-87ea-5ce32bd83b97
5202d01e-3d00-8806-87ea-5ce32bd83b97
4bc9d11e-3d00-8806-87ea-5ce32bd83b97
bcf4d21e-3d00-8806-87ea-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: