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)

019fc805-6567-7494-ae82-6d4237c71e0d
019fc805-6567-763e-80f7-43b2265a4373
019fc805-6567-7775-a5ff-5f1bbfbf45b3
019fc805-6567-7894-ba61-dd41511a9d28
019fc805-6567-79aa-a0aa-79a8efcfb9bb
019fc805-6567-7ac1-adec-d02d89165e71
019fc805-6567-7bd8-882b-daadf3ed412c
019fc805-6567-7cee-a7a2-40b38eb966e9
019fc805-6567-7e05-af28-68a411c5b4f2
019fc805-6567-7f1b-a649-0188d254c15e
019fc805-6568-7032-8f9a-283be1eb923c
019fc805-6568-7150-b9b0-a626ca4588a8
019fc805-6568-7263-8b20-daf916fb87fc
019fc805-6568-7379-805e-23132a520f4f
019fc805-6568-7490-be01-b4dfddb17d51

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)

1f18f476-64a7-6f06-b4b2-4cf95d479851
1f18f476-64a8-60be-b4b2-4cf95d479851
1f18f476-64a8-61ae-b4b2-4cf95d479851
1f18f476-64a8-6280-b4b2-4cf95d479851
1f18f476-64a8-6348-b4b2-4cf95d479851
1f18f476-64a8-6410-b4b2-4cf95d479851
1f18f476-64a8-64d8-b4b2-4cf95d479851
1f18f476-64a8-6596-b4b2-4cf95d479851
1f18f476-64a8-665e-b4b2-4cf95d479851
1f18f476-64a8-6726-b4b2-4cf95d479851
1f18f476-64a8-6866-b4b2-4cf95d479851
1f18f476-64a8-6938-b4b2-4cf95d479851
1f18f476-64a8-6a00-b4b2-4cf95d479851
1f18f476-64a8-6abe-b4b2-4cf95d479851
1f18f476-64a8-6b7c-b4b2-4cf95d479851

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)

664a8c58-8f47-11f1-b4b2-4cf95d479851
664a8cb2-8f47-11f1-b4b2-4cf95d479851
664a8d16-8f47-11f1-b4b2-4cf95d479851
664a8d7a-8f47-11f1-b4b2-4cf95d479851
664a8de8-8f47-11f1-b4b2-4cf95d479851
664a8e4c-8f47-11f1-b4b2-4cf95d479851
664a8eb0-8f47-11f1-b4b2-4cf95d479851
664a8f14-8f47-11f1-b4b2-4cf95d479851
664a8f78-8f47-11f1-b4b2-4cf95d479851
664a8fdc-8f47-11f1-b4b2-4cf95d479851
664a9040-8f47-11f1-b4b2-4cf95d479851
664a90ae-8f47-11f1-b4b2-4cf95d479851
664a9112-8f47-11f1-b4b2-4cf95d479851
664a9176-8f47-11f1-b4b2-4cf95d479851
664a91da-8f47-11f1-b4b2-4cf95d479851

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)

2538ae04-6403-870d-87ea-5ce32bd83b97
329aaf04-6403-870d-87ea-5ce32bd83b97
15f3b004-6403-870d-87ea-5ce32bd83b97
adc4b104-6403-870d-87ea-5ce32bd83b97
efc1b204-6403-870d-87ea-5ce32bd83b97
e1e4b304-6403-870d-87ea-5ce32bd83b97
1c02b404-6403-870d-87ea-5ce32bd83b97
77adb504-6403-870d-87ea-5ce32bd83b97
ae1db604-6403-870d-87ea-5ce32bd83b97
16bab704-6403-870d-87ea-5ce32bd83b97
28d9b804-6403-870d-87ea-5ce32bd83b97
602fb904-6403-870d-87ea-5ce32bd83b97
f863ba04-6403-870d-87ea-5ce32bd83b97
7523bb04-6403-870d-87ea-5ce32bd83b97
3a8ebc04-6403-870d-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)

ab5cd9ff-36c6-48ad-b726-37aabde1efd6
cf09efed-8212-4c90-9dc7-ac6594523b4e
42152837-c0af-48e0-a49d-3c3c459a2d8d
85b7c8ba-7dff-4a86-be4f-0e240f40ebe8
e2bc4d18-57ed-491f-b79d-92833f1c3f81
980d7e27-5c7d-409a-8410-44c09a09adea
199d6c92-81ec-4435-b4e3-885703e3277d
cc2c1db4-4d2e-4e5c-8431-0e3f3b1b72f4
ac92524d-f7b1-4ea9-8d76-4ea6367f7c9f
1144ea64-cca1-4003-9fbd-9a4694e447d6
339c2a40-4fdc-4494-83df-5fa06c66b3b0
b331b0f3-eee2-4cc0-b2fd-b03b67e51791
8893e389-9366-4339-b00b-7edfa7de4b1d
0ee1b901-e2e7-449c-9fa7-bd64d30cc931
7db63c09-d5db-4fda-9b8c-f6ffad1960af

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: