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)

01a08a4f-b842-7b3c-a990-012b6b19bcda
01a08a4f-b842-7d59-a955-069c2ba5a5d7
01a08a4f-b842-7e94-a0fe-2bd2ab3178ab
01a08a4f-b842-7faf-b77a-12d96b448c18
01a08a4f-b843-70c5-8ae2-0906eef1d320
01a08a4f-b843-71dc-ae9f-741b2b384cf5
01a08a4f-b843-72ee-a909-121632228e4f
01a08a4f-b843-7400-9cbd-3cb793304559
01a08a4f-b843-7513-b894-703d5002d7fc
01a08a4f-b843-7625-b4a0-93ed8c2c42a2
01a08a4f-b843-7734-8fb3-e17b217ba8b6
01a08a4f-b843-784a-9acf-4eb1256fa668
01a08a4f-b843-7961-8df7-05c7c658aae7
01a08a4f-b843-7a73-bf7b-cf1adc48e3b8
01a08a4f-b843-7b86-80ed-bd7b77f24a65

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)

1f1acecd-d8f1-6b7c-a03e-4cf95d479851
1f1acecd-d8f1-6d3e-a03e-4cf95d479851
1f1acecd-d8f1-6e2e-a03e-4cf95d479851
1f1acecd-d8f1-6f00-a03e-4cf95d479851
1f1acecd-d8f1-6fc8-a03e-4cf95d479851
1f1acecd-d8f2-6086-a03e-4cf95d479851
1f1acecd-d8f2-6144-a03e-4cf95d479851
1f1acecd-d8f2-6202-a03e-4cf95d479851
1f1acecd-d8f2-62c0-a03e-4cf95d479851
1f1acecd-d8f2-637e-a03e-4cf95d479851
1f1acecd-d8f2-64be-a03e-4cf95d479851
1f1acecd-d8f2-659a-a03e-4cf95d479851
1f1acecd-d8f2-6658-a03e-4cf95d479851
1f1acecd-d8f2-6716-a03e-4cf95d479851
1f1acecd-d8f2-67d4-a03e-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)

dd8f28b0-acec-11f1-a03e-4cf95d479851
dd8f290a-acec-11f1-a03e-4cf95d479851
dd8f296e-acec-11f1-a03e-4cf95d479851
dd8f29dc-acec-11f1-a03e-4cf95d479851
dd8f2a36-acec-11f1-a03e-4cf95d479851
dd8f2a9a-acec-11f1-a03e-4cf95d479851
dd8f2afe-acec-11f1-a03e-4cf95d479851
dd8f2b58-acec-11f1-a03e-4cf95d479851
dd8f2bbc-acec-11f1-a03e-4cf95d479851
dd8f2c16-acec-11f1-a03e-4cf95d479851
dd8f2c7a-acec-11f1-a03e-4cf95d479851
dd8f2cde-acec-11f1-a03e-4cf95d479851
dd8f2d42-acec-11f1-a03e-4cf95d479851
dd8f2da6-acec-11f1-a03e-4cf95d479851
dd8f2e00-acec-11f1-a03e-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)

ec087523-db01-8d0f-87ea-5ce32bd83b97
7cb47623-db01-8d0f-87ea-5ce32bd83b97
cda97723-db01-8d0f-87ea-5ce32bd83b97
cc6c7823-db01-8d0f-87ea-5ce32bd83b97
e8e97a23-db01-8d0f-87ea-5ce32bd83b97
7d8d7b23-db01-8d0f-87ea-5ce32bd83b97
3e1c7c23-db01-8d0f-87ea-5ce32bd83b97
81b77d23-db01-8d0f-87ea-5ce32bd83b97
25f87e23-db01-8d0f-87ea-5ce32bd83b97
53557f23-db01-8d0f-87ea-5ce32bd83b97
18ee8023-db01-8d0f-87ea-5ce32bd83b97
00328123-db01-8d0f-87ea-5ce32bd83b97
d8728223-db01-8d0f-87ea-5ce32bd83b97
a8a58323-db01-8d0f-87ea-5ce32bd83b97
38a98423-db01-8d0f-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)

b5dfeb5c-5760-4201-a732-97460b974e4c
2b036bae-fcc0-4756-bb44-19bc713dae36
3d07170f-5248-4cc1-ab67-e951c22d1267
2f796424-038d-4a40-b5a8-8e311b3a9f97
6b89cae8-b52f-4dcc-9bfa-2c2d643b0d65
68bb7e95-6ba1-4b22-b15c-5bd2c59ddfea
75634095-576d-436b-96ff-8a704a5f4171
7b1aa07a-2ccc-458c-932b-aaf76f47e3b5
107f0bbf-f7be-48d9-9679-1f9a7fdaf181
a3d4247d-76cd-44bf-8dd8-a48224ebb4b3
f3517cee-eae4-41ef-ad17-b6f731c19311
08876a91-90c4-44e4-991d-f211596b3b31
9d0138cd-49ee-4d37-bd92-1c696d93fa8b
b73ef586-e8f1-44aa-89c5-3a36cf274175
f7dd6d8b-75de-4936-9457-e0c012264331

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: