UUID generator

This UUID generator creates cryptographically secure, universally unique identifiers (UUIDs) that follow the RFC 4122 standard. Whether you need identifiers for database records, API endpoints, distributed systems, or any application requiring unique identification, this tool generates UUIDs that are virtually guaranteed to be unique across time and space.

This tool allows you to generate between 1 and 100 UUIDs at once, enabling efficient creation of multiple identifiers for batch operations or testing purposes. You can choose from various output formats to match your specific requirements. The default format is lowercase with hyphens, producing standard UUIDs like 550e8400-e29b-41d4-a716-446655440000. For systems that prefer uppercase letters, you can select the uppercase with hyphens option. When working in space-constrained environments, the no-hyphens format provides a compact 32-character representation without separators. The with braces option wraps UUIDs in curly braces for certain programming contexts, while the URN format provides the full Uniform Resource Name format suitable for semantic web applications.

What are UUIDs and why are they important?

A UUID (Universally Unique Identifier) is a 128-bit identifier that is designed to be unique across time and space. UUIDs are also known as GUIDs (Globally Unique Identifiers) in some contexts. These identifiers are crucial in modern software development for several reasons.

UUIDs are designed to be globally unique, meaning the probability of generating the same UUID twice is astronomically low. This makes them perfect for distributed systems where multiple servers or applications might generate identifiers simultaneously. Unlike sequential IDs that require a central authority to assign numbers, UUIDs can be generated independently by any system without coordination. This eliminates bottlenecks and single points of failure.

UUIDs work across different databases and systems, making them ideal for data migration, replication, and integration scenarios. When generated using cryptographically secure random number generators (as this tool does), UUIDs are unpredictable and cannot be guessed, providing an additional layer of security.

UUID v4 specification

This generator creates UUID v4 identifiers, which are randomly generated and follow the RFC 4122 standard. The structure of a UUID v4 is:

xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx

Where:

• x represents any hexadecimal digit (0-9, a-f)
• The digit 4 in the third group indicates this is a version 4 UUID
• The digit y in the fourth group is one of 8, 9, A, or B, indicating the variant

The version 4 UUID uses cryptographically secure random numbers for all bits except the version and variant bits, ensuring maximum randomness and uniqueness.

Common use cases

UUIDs serve as excellent primary keys in databases, especially in distributed systems where multiple servers might insert records simultaneously. REST APIs commonly use UUIDs to identify resources, providing a clean and secure way to reference data without exposing internal database IDs. For file management, UUIDs can be used to create unique filenames, preventing conflicts when multiple users upload files with the same name.

Web applications rely on UUIDs for session management, ensuring that each user session has a unique identifier. In distributed messaging systems, UUIDs help track messages across multiple services and ensure no message is processed twice. Microservice architectures benefit from UUIDs as they help maintain data consistency across different services without requiring centralized ID generation.

Security and privacy

This UUID generator uses the Web Crypto API (window.crypto.getRandomValues()) to ensure cryptographically secure random number generation. The UUIDs are generated entirely in your browser and are never transmitted to our servers. This means your UUIDs remain private and secure, with no server-side storage or logging of generated identifiers. The tool provides true randomness from your device's secure random number generator without requiring any network requests for generation.

Format considerations

The lowercase with hyphens format is the most common and widely supported across programming languages and databases. It's human-readable and follows the RFC 4122 standard exactly. Some systems prefer uppercase UUIDs, particularly in enterprise environments or when working with case-sensitive systems. The no-hyphens format is useful when space is limited or when working with systems that don't handle hyphens well, resulting in a 32-character representation instead of 36.

Some programming languages and frameworks expect UUIDs wrapped in braces, particularly in Windows environments or when working with certain APIs. The Uniform Resource Name format is used in semantic web applications and when you need to reference UUIDs as URIs. This format is particularly useful for RDF data, linked data, and other semantic web applications.

Performance and scalability

UUIDs are designed for high-performance, distributed systems. They can be generated at rates of thousands per second on modern hardware, making them suitable for high-throughput applications. The random nature of UUID v4 means there's no coordination required between different systems generating UUIDs, allowing for unlimited horizontal scaling.

Related tools

• Random number generator: Generate a list of random whole numbers within a specified range. Useful for testing, lotteries, or data experiments.

Further reading

• IETF: RFC 4122, A Universally Unique IDentifier (UUID) URN Namespace
• Wikipedia: Universally unique identifier

Widget made with staark