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)

01a0797d-c3cb-7d86-bf98-6870808195ba
01a0797d-c3cb-7f40-b490-7f62ef782bbc
01a0797d-c3cc-7084-bc63-ae4b79b30aa2
01a0797d-c3cc-719e-b8e3-64168d2ce800
01a0797d-c3cc-72b1-bee5-c8e4f7a99972
01a0797d-c3cc-73c3-b853-a960906d9927
01a0797d-c3cc-74e2-9ae0-95cfb1c590f1
01a0797d-c3cc-75f8-a676-030b87e6b33e
01a0797d-c3cc-770b-9ade-52b2d90e0623
01a0797d-c3cc-7821-98df-2802ab247324
01a0797d-c3cc-7934-a13a-907014186fdd
01a0797d-c3cc-7a42-b326-84036eccdb0b
01a0797d-c3cc-7b54-8457-6695ceccc7b5
01a0797d-c3cc-7c67-bb34-52f3863a626d
01a0797d-c3cc-7d79-b1f9-853c1eb09d79

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)

1f1aa5bd-431b-67ee-92ba-4cf95d479851
1f1aa5bd-431b-69d8-92ba-4cf95d479851
1f1aa5bd-431b-6ac8-92ba-4cf95d479851
1f1aa5bd-431b-6ba4-92ba-4cf95d479851
1f1aa5bd-431b-6c76-92ba-4cf95d479851
1f1aa5bd-431b-6d48-92ba-4cf95d479851
1f1aa5bd-431b-6e24-92ba-4cf95d479851
1f1aa5bd-431b-6eec-92ba-4cf95d479851
1f1aa5bd-431b-6fb4-92ba-4cf95d479851
1f1aa5bd-431c-607c-92ba-4cf95d479851
1f1aa5bd-431c-6270-92ba-4cf95d479851
1f1aa5bd-431c-634c-92ba-4cf95d479851
1f1aa5bd-431c-6414-92ba-4cf95d479851
1f1aa5bd-431c-64e6-92ba-4cf95d479851
1f1aa5bd-431c-65ae-92ba-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)

d431c68a-aa5b-11f1-92ba-4cf95d479851
d431c6f8-aa5b-11f1-92ba-4cf95d479851
d431c75c-aa5b-11f1-92ba-4cf95d479851
d431c7c0-aa5b-11f1-92ba-4cf95d479851
d431c82e-aa5b-11f1-92ba-4cf95d479851
d431c892-aa5b-11f1-92ba-4cf95d479851
d431c900-aa5b-11f1-92ba-4cf95d479851
d431c96e-aa5b-11f1-92ba-4cf95d479851
d431c9dc-aa5b-11f1-92ba-4cf95d479851
d431ca40-aa5b-11f1-92ba-4cf95d479851
d431caa4-aa5b-11f1-92ba-4cf95d479851
d431cb08-aa5b-11f1-92ba-4cf95d479851
d431cb62-aa5b-11f1-92ba-4cf95d479851
d431cbc6-aa5b-11f1-92ba-4cf95d479851
d431cc2a-aa5b-11f1-92ba-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)

43856514-5c00-8a0f-87ea-5ce32bd83b97
b4836614-5c00-8a0f-87ea-5ce32bd83b97
525b6714-5c00-8a0f-87ea-5ce32bd83b97
f0716814-5c00-8a0f-87ea-5ce32bd83b97
d1f96914-5c00-8a0f-87ea-5ce32bd83b97
468c6b14-5c00-8a0f-87ea-5ce32bd83b97
320b6c14-5c00-8a0f-87ea-5ce32bd83b97
45e46d14-5c00-8a0f-87ea-5ce32bd83b97
73a56e14-5c00-8a0f-87ea-5ce32bd83b97
ffae6f14-5c00-8a0f-87ea-5ce32bd83b97
2d257014-5c00-8a0f-87ea-5ce32bd83b97
e34c7114-5c00-8a0f-87ea-5ce32bd83b97
61867214-5c00-8a0f-87ea-5ce32bd83b97
b2dc7314-5c00-8a0f-87ea-5ce32bd83b97
90917414-5c00-8a0f-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)

faf7581c-9a39-495a-a1c8-5735623fbdcd
a1c4d0e6-b27c-413e-a731-671ec6c025a2
fe8d947f-252a-4e6b-9157-4e7eba2f486d
e1d69a0e-42ec-4dbd-af9f-ec6c1ca1ac2d
bca086a0-8c9f-4007-9759-4203df6605ab
1d1f835d-1c56-48a4-bb91-36e9576ce490
c90fb3b0-23e5-44d1-b23a-b8abe115662d
0e8f1072-f0a9-4390-8df1-55e0bb3071a7
12bfcf60-aa0a-4b5a-a138-b54e1d8a061c
de34e680-a91b-4c14-81ec-aa59d5d5bc0e
d69ee832-61f1-4ccf-8b32-f7040955c7e1
727bdf38-d039-4dba-8bb4-18194bc4dd69
b2e776ca-8a5b-4c52-9d26-ec9eda37672c
4a9e9ea7-046f-4a40-9245-635fa9b40fc7
5e18d243-e47b-467b-9eec-3cda9b5a3672

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: