UUID Generator

WebToola

Generate random version 4 UUIDs using the browser’s cryptographic random number generator.

About the UUID Generator

The UUID Generator creates random version 4 UUIDs (UUID v4) directly in your browser. Enter the number of UUIDs you need and generate multiple identifiers at once.

UUID v4 values are generated primarily from random data and are commonly used when applications need identifiers that can be created independently without relying on a central sequential ID generator.

WebToola uses the browser’s cryptographic random number generator to generate the random values used for these UUIDs.

How to Generate a UUID

Enter the number of UUIDs you want to create and run the generator. Each generated value is a version 4 UUID.

For example, requesting three UUIDs may produce results such as:

7921815e-e740-4d3f-acbf-d732dca5f31e
262118b1-d951-4204-b40b-73fbc0a8a89e
3bebaa65-48a4-441b-8dc7-3eacf1af0f3c

Because UUID v4 values contain random data, newly generated UUIDs will normally be different each time you use the tool.

What Is a UUID?

A UUID (Universally Unique Identifier) is a 128-bit identifier represented in a standardized textual format.

A UUID typically looks like this:

7921815e-e740-4d3f-acbf-d732dca5f31e

The familiar UUID string contains hexadecimal characters arranged into five groups separated by hyphens:

8-4-4-4-12

This results in the familiar 36-character textual representation, including four hyphens.

UUIDs are designed to make it practical for different systems to generate identifiers independently with an extremely low probability of accidental duplication.

What Is a Version 4 UUID?

A version 4 UUID, commonly written as UUID v4, is a UUID whose variable bits are generated randomly or pseudorandomly, with designated bits set to identify the UUID version and variant.

You can recognize the version in the standard textual representation by looking at the first character of the third group.

For example:

7921815e-e740-4d3f-acbf-d732dca5f31e
              ↑

The third group begins with 4, identifying it as a version 4 UUID.

UUID v4 is useful when an application needs identifiers without deriving them from a sequential database number, timestamp or other application-specific value.

Are UUID v4 Values Unique?

UUID stands for Universally Unique Identifier, but it is more precise to say that properly generated UUID v4 values have an extremely low probability of collision rather than claiming that duplication is absolutely impossible.

A UUID contains 128 bits in total. In UUID v4, some bits are reserved for the version and variant, leaving 122 random bits.

That provides:

2¹²² possible random combinations

This enormous space makes accidental collisions extraordinarily unlikely when UUID v4 values are generated using a suitable random source.

Common Uses for UUIDs

UUIDs are widely used in software development when applications need identifiers that can be generated without coordinating with a single central sequence.

Common examples include identifiers for database records, API resources, distributed systems, application objects, files, events and temporary data.

They can be particularly useful when different devices, services or application instances need to generate identifiers independently.

A UUID should still be treated as an identifier, however, rather than automatically being treated as a password, authentication token or other secret.

Frequently Asked Questions

What does UUID stand for?

UUID stands for Universally Unique Identifier. It is a 128-bit identifier commonly used to identify data and resources in software systems.

What is a UUID v4?

UUID v4 is version 4 of the UUID format. Its variable bits are generated using random or pseudorandom values, while specific bits identify the UUID’s version and variant.

What does a UUID v4 look like?

A UUID v4 typically looks like:

7921815e-e740-4d3f-acbf-d732dca5f31e

It uses hexadecimal characters arranged in groups following the pattern:

xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx

Here, the 4 indicates UUID version 4, while the y position is constrained by the UUID variant.

How long is a UUID?

A UUID is a 128-bit value. Its conventional textual representation contains 32 hexadecimal digits plus four hyphens, for a total of 36 characters.

Can two UUID v4 values ever be the same?

A collision is theoretically possible, but the probability is extremely small when UUID v4 values are generated correctly using a suitable random source.

For that reason, it is better to describe UUIDs as having an extremely low collision probability rather than saying duplicates are impossible.

Can I generate multiple UUIDs at once?

Yes. Enter the number of UUIDs you need, and WebToola will generate multiple UUID v4 values in one operation.

Are UUIDs case-sensitive?

UUIDs are commonly displayed using lowercase hexadecimal letters, as in WebToola’s examples. Uppercase and lowercase hexadecimal characters represent the same underlying hexadecimal values when parsing a UUID according to the standard UUID representation.

Can I use a UUID as a password or security token?

A UUID is primarily an identifier and should not automatically be treated as a password, authentication credential or secret token. Security-sensitive values should be designed according to the requirements of the authentication or security system involved.

Does WebToola send or store the generated UUIDs?

No. The UUID Generator runs in your browser and does not send or save your inputs or generated UUIDs.