What is a UUID?

A UUID (Universally Unique Identifier)—also known as a GUID (Globally Unique Identifier) in the Microsoft ecosystem—is a 128-bit number used to identify information in computer systems.

The probability of duplicating a UUID is so close to zero that you could generate 1 billion UUIDs per second for the next 85 years and practically never have a collision.

Why use Version 4 (v4)?

This tool generates Version 4 UUIDs. Unlike Version 1 (which uses your computer’s MAC address and timestamp), Version 4 is generated using purely random numbers. This makes it safer for privacy and ideal for modern applications:

• Database Primary Keys: Use them as IDs in SQL or NoSQL databases to avoid ID conflicts when merging distributed data.
• Session Tokens: Create unique, unguessable tokens for user logins and API authentication.
• Filenames: Ensure uploaded files never overwrite each other on servers (e.g., image-550e8400.png).

UUID vs. GUID: What is the difference?

There is essentially no technical difference. GUID is simply the term preferred by Microsoft (C#, .NET, SQL Server), while UUID is the standard term used in Linux, Java, and JavaScript environments. The output format (32 hexadecimal characters) is identical.