webinstall.dev/uuidv7 Star on GitHub

To update or switch versions, run webi uuidv7@stable.

Cheat Sheet

uuidv7 exists because somebody was tired of searching "UUID v7 generator" just to get a test value for a little ditty now and then. Though, the time spent creating it will probably never be recouped...

uuidv7

01928d73-d8ed-7211-a314-7081d763271d

Table of Contents

• Files
• Generating Many UUIDv7s
• Roll Your Own UUID v7 Generator
• Understanding the UUID v7 spec
  • UUID v7, by the String
  • UUID v7, by the Byte

Files

These are the files / directories that are created and/or modified with this install:

~/.config/envman/PATH.env
~/.local/bin/uuidv7
~/.local/opt/uuidv7/

How to Generate Many v7 UUIDs at Once

uuidv7 ; uuidv7 ; uuidv7

01928d74-3ff7-796f-8417-0fee6da50a5a
01928d74-3ff9-73f7-8ce1-71e741cfa56f
01928d74-3ffb-7e06-abe9-3fe20e5cb5f2

How could I roll my own UUID v7 generator?

It's not that hard. There are examples in many languages here:

• https://github.com/coolaj86/uuidv7

See the simplified spec examples below.

What's the UUID v7 spec, in simple terms?

See the explanation here:

• https://github.com/coolaj86/uuidv7

A snapshot of that is copied here, for convenience:

UUID v7, by the Characters

There are 36 characters total: 32 hex (0123456789abcdef) + 4 dashes (-)

  8 time    4 time    1v + 3ra   ½v + 3½rb    12 random b
019212d3  -  87f4   -   7d25   -   902e   -   b8d39fe07f08

• 8ch hex time high
• -
• 4ch hex time low
• -
• 4ch hex version + "random a"
  • 1ch hex version: 7
  • 3ch hex "random a"
• -
• 4ch hex variant + "random b"
  • 1ch hex version: 8, 9, a, b
  • 3ch hex "random b"
• -
• 12ch hex randam a
  • 4ch hex random a
  • 8ch hex random a

UUID v7, by the Bits

There are 128 bits total:
48 time and 80 random, with 4 version and 2 variant bits substituted

   48 time         4ver, 12ra   2var, 14rb        random b
019212d3-87f4    -    7d25    -    902e    -    b8d39fe07f08

• 48 bits of timestamp
  • 32-bit high (minutes to years)
  • 16-bit low (seconds & milliseconds)
• 16 bits of version + random
  • 4-bit version (0b0111)
  • 12-bit random
• 64-bits variant + random
  • 2-bit variant (0b10)
  • 62-bit random