UUID vs GUID: What Is the Difference?

If you've spent time in software engineering, you have likely heard both UUID (Universally Unique Identifier) and GUID (Globally Unique Identifier) used to describe 36-character random strings. But is there an actual difference?

The Short Answer

Practically speaking, there is no difference. Today, the terms are used interchangeably. A GUID is simply Microsoft's implementation and terminology for the UUID standard.

The History

The term UUID was created by the Open Software Foundation (OSF) as part of their Distributed Computing Environment (DCE) in the 1990s. The goal was to have an identifier that could be generated independently across a network without coordination.

When Microsoft adopted this architecture for their Component Object Model (COM) in Windows, they termed it GUID (Globally Unique Identifier). For a time, there were minor differences in how certain bytes were structured due to endianness (the order in which bytes are stored in memory on different hardware architectures).

Modern Usage

In modern development environments (like .NET, Java, Node.js, and Python), generating a GUID or generating a UUID results in the exact same 128-bit identifier format (RFC 4122). Which acronym you use usually depends on your tech stack:

• Microsoft/C# Developers: Tend to say GUID.
• Linux/Java/JavaScript Developers: Tend to say UUID.

Test it Yourself

Whether you need a GUID or a UUID, our UUID Generator produces standard RFC 4122 compliant identifiers that work flawlessly across all platforms.