UUID Generator

Generated 2 version 4 UUID(s).

How it works

• Drew 16 random bytes.
• Set the version nibble to 4 and the RFC variant bits.
• Formatted the 16 bytes as 8-4-4-4-12 lowercase hexadecimal.

• Version 4 UUIDs are random; they carry no ordering information.

Methodology

1. Generate UUID version 4 identifiers from 122 random bits, or version 7 identifiers from a millisecond timestamp plus random bits, per RFC 9562.
2. Set the version and variant bits so the identifier is a valid RFC 9562 UUID.
3. Use a seeded generator only for reproducible tests and documentation; production output uses the platform random source.

Time model

• Time source: UTC.
• Timezone: A version 7 timestamp is milliseconds since the Unix epoch (UTC). The identifier is an absolute value and carries no local timezone.
• Locale: Epoch milliseconds are locale-independent; no locale formatting applies.
• Daylight saving: UTC has no daylight-saving transitions; a version 7 timestamp is unaffected by DST.
• Reference date: Version 7 uses an explicit 48-bit epoch-millisecond timestamp when supplied; otherwise it uses the current instant read from the visitor's environment at runtime. Version 4 uses no time.

Usage

1. Choose version 4 for purely random identifiers or version 7 for sortable, time-ordered ones.
2. Choose how many identifiers to generate (1 to 100).
3. Copy the results.

Examples

These are examples, not current values: they use fixed inputs, while the interactive tool computes live results in your browser.

Two reproducible v4 UUIDs

{
  "version": "v4",
  "count": 2,
  "seed": "example"
}

Time-ordered v7

{
  "version": "v7",
  "count": 1,
  "seed": "example",
  "timestamp": 1735689600000
}

Limitations

What a UUID actually guarantees

A UUID is an identifier, not a secret. Version 4 carries 122 random bits and version 7 carries a timestamp plus random bits; both are designed to be unique, not unguessable.