Online UUID Generator

Generate UUIDs online and allows practically unique identification of information in distributed systems. Supports all major versions.

Version 4 UUID:

Version 1 UUID Generator

Version 3 UUID Generator

Version 4 UUID Generator

Version 5 UUID Generator

Which is?

UUID is a universal unique identifier used to identify anything in the computing world. UUID is a 128-bit number, represented by 32 hexadecimal digits, displayed in five groups separated by hyphens, the text format is 8-4-4-4-12, a total of 36 characters (32 alphanumeric characters and 4 hyphens).
E.g:
36614423-8e61-41ab-9ec8-29d211738cf2

The word "unique" should be taken to mean "practically unique" since the identifiers have a finite size, it is possible for two different items to share the same identifier. The size and the process of generating the identifier need to be selected in order to make this improbability sufficient in practice.

Which UUID version to use?

UUID — (from English: Universally Unique IDentifier )

Basically, there are two different needs to generate a UUID:
  1. If you only need a unique ID, use version 1 or 4.
  2. If you always need to generate the same UUID from a given name, use version 3 or 5.
Below are the technologies for generating each version of the UUID.

UUID v1

UUID v1 is generated by combining the host's MAC address with the current date and time. In addition, it also uses another random component to guarantee its exclusivity. These UUID v1 are easy to predict (given one, I may be able to guess the other) and can be traced back to your network card. It is not recommended to create these. You will certainly get a totally unique ID, unless you generate the ID on the same computer at the same time. In this case, the chance of collision changes from impossible to very small due to random bits.

UUID v4

The generation of v4 UUID is much easier. The bits containing UUID v4 are randomly generated and have no inherent logic. Therefore, it is not possible to identify information about the source by looking at the UUID.

UUID v3

UUID v3 is generated by providing two input information, an "Input string" being any string that can be changed in your application and a "Namespace" being a fixed UUID used in conjunction with the input string to distinguish UUIDs generated in different applications. This will generate a unique ID from the MD5 hash of the namespace and name. If you need backward compatibility (compatible with another system that generates UUIDs from names), use this feature.

UUID v5

Unlike versions 1 or 4, UUID v5 is generated by providing two input information, an "Input string" being any string that can be changed in your application and a "Namespace" being a fixed UUID used in conjunction with the input string to distinguish UUIDs generated in different applications. Use the SHA1 hash algorithm to convert this two information into UUID. The important thing to note is that the UUID v5 is consistent. This means that any combination of input and namespace will produce the same UUID each time.