A GUID — Globally Unique Identifier — is a 128-bit value designed to be unique across every computer on earth. You have seen them everywhere: database keys, Windows registry entries, API tokens, and software licenses.

The standard format is 32 hexadecimal characters in five groups, like 550e8400-e29b-41d4-a716-446655440000. Version 4 GUIDs are randomly generated, and the odds of two colliding are so small you can ignore them entirely.

Developers use GUIDs as primary keys, session tokens, and transaction IDs — anywhere a unique reference is needed without a central counter. Most programming languages have a one-line function to create them.

Need one right now? Generate as many version 4 GUIDs as you want free, in uppercase or lowercase, with or without braces.