UUID Generator

A UUID (Universally Unique Identifier) is a string of characters that is used to uniquely identify an object. You may also see the term GUID (Globally Unique Identifier) which is also commonly used. Both UUIDs and GUIDs are generated according to a standard, using a combination of random numbers, timestamps and algorithms, all of which makes it extremely unlikely that two values will be equal. It is based on the RFC 4122 standard.

Data types specified as UUID are expected to be in a valid string representation of a universally unique identifier (UUID). The API specifically expects the UUID to be provided in its canonical form which is represented by 32 lowercase hexadecimal digits displayed in five groups separated by hyphens.

This representation takes the form of 8-4-4-4-12 for a total of 36 characters, 32 hexadecimal characters and four hyphens. In case you are converting an array of bytes, the break down of bytes for the hexadecimal String is 4-2-2-2-6. UUIDs are version 4.

Example of a UUID in the expected canonical string format in a JSON request or response body.

Example of a UUID being provided as a URL segment for an API.

Here are some common use cases for generating a version 4 UUID:

• Database Records: Version 4 UUIDs can be used as unique identifiers for records in databases. They ensure that each record has a unique identifier without relying on sequential numbers or other potentially conflicting identifiers.
• Distributed Systems: In distributed systems where multiple nodes or processes operate independently, version 4 UUIDs can be used to generate unique identifiers for events, transactions, or messages. This allows different components to operate autonomously and later correlate events based on their unique identifiers.
• Web Applications: Version 4 UUIDs can be used as unique identifiers for various entities in web applications. For example, they can be assigned to user accounts, session IDs, or resources like images, files, or documents. This helps avoid conflicts when multiple users or processes are creating or accessing resources simultaneously.
• Message Queues: When messages are passed between different components or services through a message queue system, version 4 UUIDs can be used as unique message IDs. This helps track and identify messages as they move through the system, enabling reliable message processing and tracking.
• Testing and Development: Version 4 UUIDs are often used in testing and development environments. They can be used as placeholder or mock identifiers when creating test data or simulating scenarios. Using UUIDs ensures that the test data is unique and avoids clashes with existing production data.
• Security and Authentication: Version 4 UUIDs can be used in security-related scenarios such as generating secure tokens, session IDs, or API keys. These identifiers can be used to validate and authorize access to resources, authenticate users, or secure communication channels.
• Logging and Tracking: Version 4 UUIDs can be used as unique identifiers for log entries, trace information, or audit trails. They enable efficient tracking and correlation of log messages across multiple systems or services, facilitating debugging and troubleshooting activities.

This UUID generator generates a version 4 universally unique identifier. A version 4 UUID is made up of 32 hexadecimal characters (128 bits), divided into five groups separated by hyphens in this format: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx. You may also see this written as 8-4-4-4-12.

The main advantage of version 4 UUIDs is that they are generated using random numbers, which makes it extremely unlikely that two UUIDs will be the same.

How unlikely? To be specific, a UUID is 16 bytes or 128 bits. Out of these 128 bits, 4 are used to indicate the version, and another 2 indicate the variant. This leaves us with 122 bits, and as a result we have 2^122 possible combinations, or 5.3 undecillion, or 5.31x10^36 (or a 5 with 36 zeros behind it). That is a lot. When we begin talking about numbers in this range - the probability that a duplicate value will be generated is essentially zero.

This makes UUIDs perfect for use as a unique object identifier in software programs, database records, and other situations where a unique identifier is needed.

One way to think about a version 4 UUID collision is like this:

Only after generating 1 billion UUIDs every second for the next 100 years, the probability of creating just one duplicate would be about 50%. Or, to put it another way, the probability of one duplicate would be about 50% if every person on earth owned 600 million UUIDs.