GUID / UUID Generator

The GUID/UUID Generator creates unique 128-bit identifiers that are essential for software development, database systems, and distributed applications. This tool supports multiple UUID versions, output formats, and batch generation, making it the most comprehensive UUID generator available online.

What is a UUID/GUID?

A UUID (Universally Unique Identifier) or GUID (Globally Unique Identifier) is a 128-bit number used to uniquely identify information in computer systems. These identifiers are designed to be unique across time and space without requiring a central registration authority.

UUIDs follow the RFC 4122 standard and are represented as 32 hexadecimal digits displayed in five groups separated by hyphens: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx

UUID Structure

UUID Versions Explained

Version 1 (Time-based)

UUID v1 is generated using the current timestamp and the MAC address of the computer. This provides temporal ordering and near-guaranteed uniqueness, but may expose hardware identity. Best for distributed systems that need time-ordered identifiers.

Version 4 (Random)

UUID v4 is generated using cryptographically strong random numbers. This is the most commonly used version for general purposes. With 122 random bits, the probability of collision is astronomically low (2.71 quintillion UUIDs for 50% collision probability).

Version 5 (Name-based SHA-1)

UUID v5 is generated by hashing a namespace identifier and a name using SHA-1. This is deterministic: the same namespace and name will always produce the same UUID. Useful for generating consistent identifiers from URLs, domain names, or other identifiable data.

GUID vs UUID: What is the Difference?

Technically, GUID and UUID refer to the same concept. GUID (Globally Unique Identifier) is the term historically used by Microsoft in Windows and .NET environments, while UUID (Universally Unique Identifier) is the more universal term defined in RFC 4122. They are functionally identical.

How to Use This Generator

1. Select UUID Version: Choose v4 (random) for most cases, v1 (timestamp) for temporal ordering, or v5 (name-based) for deterministic generation.
2. Choose Output Format: Select standard lowercase, uppercase, without hyphens, with braces, or URN format depending on your application requirements.
3. Set Quantity: Generate 1-100 UUIDs at once for bulk operations.
4. For v5: Select a namespace and enter a name to generate deterministic UUIDs.
5. Generate and Copy: Click Generate and use the copy buttons for individual UUIDs or copy all at once.

Common Use Cases

• Database Primary Keys: UUIDs are excellent for distributed databases where auto-increment IDs would conflict
• Session Tokens: Generate secure, unique session identifiers for web applications
• File and Object Naming: Create unique names for uploaded files, S3 objects, or temporary files
• API Identifiers: Use UUIDs for resource IDs in RESTful APIs
• Tracking and Analytics: Generate unique visitor IDs or event identifiers
• Message Queues: Ensure unique message IDs in distributed messaging systems

UUID Collision Probability

The probability of generating duplicate UUIDs is astronomically low. For UUID v4:

• You would need to generate 2.71 quintillion UUIDs to have a 50% probability of at least one collision
• Generating 1 billion UUIDs per second, it would take about 85 years to reach this threshold
• In practical terms, UUID collisions are negligible for all real-world applications

Frequently Asked Questions

Additional Resources

• Universally Unique Identifier - Wikipedia
• RFC 4122: A Universally Unique IDentifier (UUID) URN Namespace
• GUID Structure - Microsoft Learn