UUID Versions Explained

UUID v1 (Time-based)

Generated based on current timestamp and MAC address. Guarantees uniqueness across space and time but may reveal information about when and where it was generated.

Example: 6ba7b810-9dad-11d1-80b4-00c04fd430c8

UUID v4 (Random)

Generated using random or pseudo-random numbers. Most commonly used version. Provides good uniqueness without revealing any information about the generator.

Example: f47ac10b-58cc-4372-a567-0e02b2c3d479

Nil UUID

Special case UUID with all bits set to zero. Used to represent the absence of a UUID or as a default value.

Example: 00000000-0000-0000-0000-000000000000

UUID Format Options

Standard Format

f47ac10b-58cc-4372-a567-0e02b2c3d479

Uppercase

F47AC10B-58CC-4372-A567-0E02B2C3D479

With Braces

{f47ac10b-58cc-4372-a567-0e02b2c3d479}

No Dashes

f47ac10b58cc4372a5670e02b2c3d479

Common Use Cases

Database Records: Primary keys for database tables
API Development: Resource identifiers in REST APIs
File Systems: Unique file and directory names
Distributed Systems: Unique identifiers across multiple systems
Session Management: Unique session tokens
Software Licensing: Unique license keys and product IDs

UUID Properties

Uniqueness: Extremely low probability of duplicates
Format: 128-bit value represented as 32 hexadecimal digits
Structure: 8-4-4-4-12 character groups separated by hyphens
Standards: Defined by RFC 4122
Cross-platform: Works across different systems and languages

UUID Generator

UUID Version

Format Options

Quantity

Generated UUIDs