Free Online GUID / UUID Generator

What is a GUID?

A GUID, also called a UUID, stands for *Globally Unique Identifier* (or *Universally Unique Identifier*). It is a 128-bit value designed to uniquely label an item such as a record, object, or resource. In practice, “GUID” is more common in Microsoft-oriented environments, while “UUID” is the term used more broadly across other platforms.

How are GUIDs used?

GUIDs are widely used in software engineering and IT operations, including by developers, database administrators, QA/test teams, and systems engineers. You’ll encounter them across many stacks, including Java, C#, Python, C++, relational SQL databases, and cloud-native/non-relational databases. Typical uses include primary keys, version identifiers, component IDs, correlation IDs, and any scenario where a near-certain unique identifier is needed.

How unique is a GUID?

Because the identifier space is 128 bits, the number of possible values is enormous. Even at extremely high generation rates, the likelihood of accidentally producing the same value twice remains very low. As a rough illustration: generating around one billion identifiers per second continuously for a full year would still leave you with only about a 50% chance of seeing a single collision. Similarly, even if every person on Earth generated hundreds of millions of GUIDs, the chance of any duplicate would still be around 50%.


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