Generate UUID v4

Generate a random UUID version 4 for an opaque identifier.

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ToolUUID v4 Generator
Input
Output
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Preview

How it works

Random bytes fill a 128-bit UUID, then version and variant bits are set to identify the standard layout. The result is rendered in canonical hexadecimal groups.

  • Randomness avoids time and hardware-address leakage.
  • Only the non-version and non-variant bits carry random data.

Worked example

Single UUID v4
Generate one random UUID v4
Input
											Count: 1
Uppercase: false
Output
												293fbcf6-e0f2-494d-bcc5-83366e849778

When to use this

Database records, request correlation IDs, and test fixtures use random UUIDs.

Edge cases

  • Weak randomness reduces collision resistance.
  • Version and variant bits are fixed.
  • Hyphen changes affect presentation, not the underlying bytes.

References