What is a UUID?
A UUID (Universally Unique Identifier) is a 128-bit number used to identify information in computer systems. When generated according to standard methods, UUIDs are for practical purposes unique. Their uniqueness does not depend on a central registration authority or coordination between the parties generating them, unlike most other numbering schemes.
The term GUID (Globally Unique Identifier) is also used, typically in software created by Microsoft. Functionally, GUIDs and UUIDs are the same. This tool generates version 4 UUIDs, which are based on random numbers.
Frequently Asked Questions
Are these UUIDs truly unique?
For all practical purposes, yes. A version 4 UUID has 122 bits of randomness, which means there are 2¹²² (or 5.3 x 10³⁶) possible combinations. The probability of generating a duplicate, even in a system that creates billions of UUIDs per second, is infinitesimally small.
What is a Version 4 UUID?
Version 4 (V4) is one of the most common types of UUID. It is created using random or pseudo-random numbers. The specification for a V4 UUID requires six bits to be set to specific values (4 for the version, and 2 for the variant), leaving 122 bits for the random part. This tool uses your browser's built-in crypto.randomUUID() function, which generates cryptographically strong random values.
When should I use a UUID?
UUIDs are excellent as primary keys in databases, especially in distributed systems where auto-incrementing integers can be problematic. They are also used for unique transaction IDs, session identifiers, and any scenario where you need a unique identifier without coordinating with a central authority.
Is this generator secure?
Yes. All generation happens locally in your browser using the standard Web Crypto API (crypto.randomUUID). No information is sent to our server. The UUIDs are generated with a cryptographically secure pseudo-random number generator, making them suitable for most non-cryptographic security purposes (like session IDs).