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)

019f402b-32ba-7863-8bea-afb420c63aad
019f402b-32ba-7a52-9b86-8464b239a2f5
019f402b-32ba-7b92-9567-bf783f08e7b9
019f402b-32ba-7cad-802d-47dbdc33ae4f
019f402b-32ba-7dc7-8a90-bfbe6b091631
019f402b-32ba-7eda-8c8b-4c7862828d1f
019f402b-32ba-7ff0-9ac3-65a247469562
019f402b-32bb-710f-bddf-7a61ff9c56ab
019f402b-32bb-7225-a184-7b54c7678fab
019f402b-32bb-7338-b0f0-a1af61c2597e
019f402b-32bb-744a-aed6-1df32349d762
019f402b-32bb-755d-b8cd-f51ab0702c0a
019f402b-32bb-7673-91ba-0b7b8f96ac00
019f402b-32bb-778a-8fd6-71d6dcf827e9
019f402b-32bb-789c-ae9c-60633e1a0e77

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)

1f17a8ca-aef0-63a4-a2fa-4cf95d479851
1f17a8ca-aef0-6566-a2fa-4cf95d479851
1f17a8ca-aef0-6656-a2fa-4cf95d479851
1f17a8ca-aef0-671e-a2fa-4cf95d479851
1f17a8ca-aef0-67dc-a2fa-4cf95d479851
1f17a8ca-aef0-689a-a2fa-4cf95d479851
1f17a8ca-aef0-6958-a2fa-4cf95d479851
1f17a8ca-aef0-6a20-a2fa-4cf95d479851
1f17a8ca-aef0-6ad4-a2fa-4cf95d479851
1f17a8ca-aef0-6b92-a2fa-4cf95d479851
1f17a8ca-aef0-6ce6-a2fa-4cf95d479851
1f17a8ca-aef0-6db8-a2fa-4cf95d479851
1f17a8ca-aef0-6e76-a2fa-4cf95d479851
1f17a8ca-aef0-6f2a-a2fa-4cf95d479851
1f17a8ca-aef0-6fe8-a2fa-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)

aaef10ba-7a8c-11f1-a2fa-4cf95d479851
aaef1128-7a8c-11f1-a2fa-4cf95d479851
aaef1182-7a8c-11f1-a2fa-4cf95d479851
aaef11dc-7a8c-11f1-a2fa-4cf95d479851
aaef124a-7a8c-11f1-a2fa-4cf95d479851
aaef12ae-7a8c-11f1-a2fa-4cf95d479851
aaef1312-7a8c-11f1-a2fa-4cf95d479851
aaef1380-7a8c-11f1-a2fa-4cf95d479851
aaef13da-7a8c-11f1-a2fa-4cf95d479851
aaef143e-7a8c-11f1-a2fa-4cf95d479851
aaef1498-7a8c-11f1-a2fa-4cf95d479851
aaef14fc-7a8c-11f1-a2fa-4cf95d479851
aaef1560-7a8c-11f1-a2fa-4cf95d479851
aaef15c4-7a8c-11f1-a2fa-4cf95d479851
aaef161e-7a8c-11f1-a2fa-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)

79f9b300-4101-8d0b-87ea-5ce32bd83b97
65a9b400-4101-8d0b-87ea-5ce32bd83b97
86c1b500-4101-8d0b-87ea-5ce32bd83b97
5887b600-4101-8d0b-87ea-5ce32bd83b97
96e6b700-4101-8d0b-87ea-5ce32bd83b97
720db800-4101-8d0b-87ea-5ce32bd83b97
a451b900-4101-8d0b-87ea-5ce32bd83b97
fbd0ba00-4101-8d0b-87ea-5ce32bd83b97
012bbb00-4101-8d0b-87ea-5ce32bd83b97
8146bc00-4101-8d0b-87ea-5ce32bd83b97
49e9bd00-4101-8d0b-87ea-5ce32bd83b97
1aafbe00-4101-8d0b-87ea-5ce32bd83b97
0d2ebf00-4101-8d0b-87ea-5ce32bd83b97
41edc000-4101-8d0b-87ea-5ce32bd83b97
a309c100-4101-8d0b-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)

de4d4fc5-5649-4359-b4d8-807a25cde7f9
ec1be74b-40aa-44de-abc6-67632b5caea6
370d411d-960a-4e73-b0d8-ffe7fdc05218
c1b0c3f4-6ef8-43e3-b886-ddb8268b9f0c
af05f658-975f-4d6c-bdd7-25ce03f82f92
e100822f-e60b-4359-a781-367bb3bb4282
9e8168d2-abf5-4203-a0d7-a86ffaa940c3
75d15a81-462e-4c6e-b446-072332a5ca94
01989fbc-1c81-411d-ba5f-dcc12c3a8c90
8f9dce0c-f3cf-4b33-823c-131db6184690
fb6a990f-e7bf-46a0-ab21-a26df0fcd007
778a51c2-d057-4685-8b24-17a34a63bda5
763af201-fdb4-4007-a5c0-54f4e4343a42
a790e561-57cf-45ee-a7cc-a4041deea19f
2ebeaf9f-6b45-4d1e-be47-d106e7e5ec5a

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: