UUID (Universally Unique Identifier) is a 128-bit number used to uniquely identify information. Standard format: 8-4-4-4-12 hex digits, e.g. 550e8400-e29b-41d4-a716-446655440000.

What is the difference between UUID v4 and v1?

UUID v4 is random-based, while v1 is timestamp + MAC address based. v4 is most commonly used for general purposes.

UUID Generator - Free Online UUID v1/v4/v5

Configuration

UUID Version

v1 Timestamp v3 MD5 Name v4 Random v5 SHA1 Name NIL All Zero

Quantity

Uppercase Braces {} No Hyphens Auto-copy first

About UUID Versions

UUID v1

Time-based. Generated from current timestamp and MAC address.

550e8400-e29b-11d4-a716-446655440000

UUID v3

MD5 hash of namespace UUID + name. Deterministic.

6fa459ea-ee8a-3ca4-894e-db77e160355e

UUID v4

Random. Most commonly used for general purposes.

4e1c6a3b-9d2f-4e7a-8c1b-2a3b4c5d6e7f

UUID v5

SHA-1 hash of namespace UUID + name. Recommended over v3.

886313e1-3b8a-5372-9b90-0c9aee1993eb

NIL UUID

Special UUID with all 128 bits set to zero.

00000000-0000-0000-0000-000000000000

Configuration

About UUID Versions

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