Random UUID Generator
Generate a Single UUID v4
Bulk UUID v4 Generator
Frequently Asked Questions (FAQ)
What is a UUID?
A UUID (Universally Unique Identifier) is a 128-bit number used to identify information in computer systems. The term GUID (Globally Unique Identifier) is also used, typically in software created by Microsoft. When generated according to the 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. While the probability that a UUID will be duplicated is not zero, it is close enough to zero to be negligible.
What is UUID Version 4?
There are several versions of UUIDs, each generated differently. This tool generates Version 4 (v4) UUIDs, which are the most common type. A v4 UUID is generated from random or pseudo-random numbers. The standard defines a format of 32 hexadecimal (base-16) digits, displayed in five groups separated by hyphens, in the form 8-4-4-4-12 for a total of 36 characters (32 alphanumeric characters and four hyphens). For example: 123e4567-e89b-12d3-a456-426614174000. The core idea is that the sheer number of possible random combinations (2^122) makes it virtually impossible for two identical UUIDs to be generated independently.
Why and where are UUIDs used?
UUIDs are incredibly useful in distributed systems because they can be generated independently by different systems without the risk of collision. This avoids the need for a central authority to issue unique IDs, which can be a bottleneck. Common use cases include:
- Database Keys: Using UUIDs as primary keys in database tables allows you to merge records from different databases without key conflicts.
- Transaction IDs: In financial or logging systems, a unique ID for every transaction is crucial for tracking and auditing.
- Session Identifiers: Web applications can use UUIDs to create unique session IDs for users.
- File and Object Naming: To ensure that files uploaded to a system have unique names, preventing accidental overwrites.
Is it possible to generate the same UUID twice?
Theoretically, yes, but it is astronomically unlikely. For a v4 UUID, there are approximately 5.3 x 10^36 possible combinations. To put this into perspective, you would need to generate 1 billion UUIDs per second for about 100 years to have a 50% chance of creating just one collision. For all practical purposes in software development, you can confidently assume that every v4 UUID you generate will be unique in the universe.
