UUID Generator - Generate Random UUID v4 and GUID

A UUID (Universally Unique Identifier) is a 128-bit identifier represented as 32 hexadecimal characters, divided into 5 groups separated by hyphens. The standard format is xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx, where each x is a random hexadecimal character (0-9, a-f).

UUID version 4 (random)

This generator produces UUID v4 identifiers, the most commonly used variant. In UUID v4, virtually all bits are randomly generated, with two exceptions:

• Version nibble— The first hexadecimal character of the third group is always 4, indicating it is a version 4 UUID.
• Variant bits— The first character of the fourth group is always 8, 9, a or b (variant 1, RFC 4122).

UUID vs GUID

The terms UUID and GUID (Globally Unique Identifier) are often used interchangeably. Technically, GUID is the term Microsoft uses for the same concept. In practice, they are identical in format and functionality. In .NET and SQL Server the term GUID is used, while in most other ecosystems (Java, Python, PostgreSQL) UUID is the standard.

Common applications

• Database primary keys— UUIDs prevent collisions when merging databases or in distributed systems.
• API identifiers— Use UUIDs as resource IDs in REST APIs to avoid sequential IDs (and thereby enumeration attacks).
• Distributed systems— Multiple nodes can independently generate UUIDs without central coordination.
• Session tokens and correlation IDs— Track requests through microservices with unique UUIDs per transaction.

Use the dataset generator to combine UUIDs with other test data like BSN numbers and IBAN numbers for complete test records.