UUID and GUID Generator — What Are They?

A UUID (Universally Unique Identifier) — also called a GUID (Globally Unique Identifier) in Microsoft contexts — is a 128-bit label used to uniquely identify objects in software systems. UUID v4 uses random numbers to ensure uniqueness across systems without a central registry.

UUID v4 Format

A standard UUID looks like: 550e8400-e29b-41d4-a716-446655440000. It consists of 32 hexadecimal digits displayed in five groups separated by hyphens.

Common Uses of UUIDs / GUIDs

• Primary keys in databases (instead of auto-increment integers)
• Unique identifiers for distributed systems and microservices
• Session tokens, transaction IDs, and correlation IDs
• File names, folder names, and temporary resource identifiers
• Entity Framework and ASP.NET Core model IDs

UUID vs GUID

UUID and GUID refer to the same concept. UUID is the standard term defined by RFC 4122, while GUID is Microsoft's terminology used in COM, .NET (System.Guid), and SQL Server (uniqueidentifier).