What's the difference between UUID v1 and v4?

UUID v4 is generated using random or pseudo-random numbers, making it the most commonly used version with virtually no chance of collision. UUID v1 is generated using the current timestamp and MAC address, making UUIDs sortable chronologically but potentially exposing privacy information. For most applications, UUID v4 is recommended due to its simplicity and lack of privacy concerns.

How do I use UUIDs as database primary keys?

To use UUIDs as primary keys, generate a UUID for each new record and store it in a UUID or BINARY(16) column type for optimal performance. UUIDs work excellently in distributed databases where auto-incrementing integers aren't practical. They enable offline data generation and prevent ID conflicts when merging databases. However, ensure proper indexing as UUIDs are larger than integers and can impact query performance if not indexed correctly.

Are UUIDs truly unique?

UUID v4 has a 1 in 2^122 (approximately 5.3x10^36) chance of collision, making duplicates virtually impossible in practice. While theoretically possible to generate the same UUID twice, the probability is so infinitesimally small that it's considered unique for all practical purposes. The collision probability is comparable to winning the lottery multiple times consecutively.

Can I use UUIDs in URLs?

Yes, UUIDs can be used in URLs and are commonly used for resource identification in RESTful APIs. Use the standard format with hyphens or the no-hyphens format depending on your preference. UUIDs in URLs are ideal for public-facing resources as they don't expose information about record counts or creation order, unlike sequential integer IDs. They're also harder to guess, providing some security through obscurity.

What format should I use for UUIDs?

The standard format with lowercase and hyphens (e.g., '550e8400-e29b-41d4-a716-446655440000') is most widely supported and recommended by RFC 4122. However, uppercase is also valid, and some systems prefer no hyphens for compactness. Use braces format for Microsoft GUID compatibility, and URN format when following URN naming conventions. Choose based on your system's requirements and coding standards.

Is the UUID generator free to use?

Yes! Our UUID generator is completely free with unlimited usage. Generate as many UUIDs as you need for databases, APIs, testing, development, or any other purpose. No registration is required, there are no hidden fees, rate limits, or restrictions. All UUID generation happens locally in your browser, ensuring maximum privacy and security.

How do I validate a UUID?

Use our built-in UUID validator to check if a UUID is valid and detect its version. Simply paste the UUID into the validation field and click validate. A valid UUID must follow the RFC 4122 format: 32 hexadecimal characters in 8-4-4-4-12 grouping with hyphens. The validator checks format correctness and identifies whether it's a v1, v4, Nil, or other version UUID.

Can I generate multiple UUIDs at once?

Yes! Our bulk generation feature allows you to create up to 100 UUIDs simultaneously. Select your desired count (1, 5, 10, 25, 50, or 100), choose the UUID version and format, then click generate. You can copy all UUIDs at once or download them as a text file for use in scripts, databases, testing, or data seeding operations.

A Nil UUID is a special UUID where all bits are set to zero: '00000000-0000-0000-0000-000000000000'. It's defined by RFC 4122 and used as a placeholder value or to represent an undefined/null UUID in databases and applications. Think of it as the UUID equivalent of null or zero for regular integers. It's useful for initialization, default values, or indicating missing data.

UUID Generator - Create Unique Identifiers Instantly

Generate universally unique identifiers (UUIDs) for your applications. Supports UUID v1, v4, and custom formats.

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UUID Validator

Free UUID Generator Tool

Generate universally unique identifiers (UUIDs) instantly with our free online UUID generator. Perfect for developers, database administrators, and anyone needing unique identifiers for their applications, APIs, or data structures.

Our tool supports multiple UUID versions including v4 (random), v1 (timestamp-based), and Nil UUIDs. Generate single or bulk UUIDs in various formats, validate existing UUIDs, and download results for later use. All generation happens locally in your browser for maximum privacy and security.

What is a UUID?

A UUID (Universally Unique Identifier) is a 128-bit number used to uniquely identify information in computer systems. UUIDs are standardized by the Open Software Foundation (OSF) as part of the Distributed Computing Environment (DCE).

UUIDs are designed to be unique across both space and time without requiring a central registration authority. They're commonly used as database primary keys, session identifiers, file names, and anywhere else a unique identifier is needed. The standard format displays 32 hexadecimal digits in five groups separated by hyphens: 8-4-4-4-12.

UUID Versions Explained

UUID v4 (Random): The most commonly used version. Generated using random or pseudo-random numbers. Each UUID has a 1 in 2^122 chance of collision, making duplicates virtually impossible. Ideal for most applications requiring unique identifiers.

UUID v1 (Timestamp): Generated using the current timestamp and MAC address. Includes time-based components making them sortable chronologically. Useful when you need time-ordered identifiers, though less commonly used due to privacy concerns (MAC address exposure).

Nil UUID: A special UUID where all bits are set to zero (00000000-0000-0000-0000-000000000000). Used as a placeholder or to represent an undefined/null UUID value in databases and applications.

Common Use Cases

Database Primary Keys: Use UUIDs as primary keys in distributed databases where auto-incrementing integers aren't practical. Enables offline data generation and prevents ID conflicts when merging databases.

API Development: Generate unique request IDs, session tokens, and resource identifiers for RESTful APIs and microservices. Perfect for tracking requests across distributed systems.

File Management: Create unique filenames for uploads, cache keys, and temporary files without risk of collision. Particularly useful in cloud storage and content delivery networks.

Testing & Development: Generate test data, mock objects, and sample datasets with unique identifiers. Useful for unit tests, integration tests, and development environments.

Why Use Our UUID Generator?

✓Multiple Versions: Generate UUID v1, v4, and Nil UUIDs based on your specific requirements.
✓Bulk Generation: Create up to 100 UUIDs at once for testing, data seeding, or batch operations.
✓Multiple Formats: Choose from standard, uppercase, no-hyphens, braces, and URN formats to match your coding standards.
✓UUID Validator: Validate existing UUIDs and detect their version to ensure data integrity.
✓One-Click Copy: Copy individual UUIDs or all generated UUIDs to clipboard instantly.
✓Download Support: Export generated UUIDs to a text file for use in scripts, databases, or documentation.
✓100% Private: All UUID generation happens locally in your browser - no data is sent to servers.
✓Free & Unlimited: Generate unlimited UUIDs with no registration, restrictions, or hidden costs.

UUID Best Practices

•Use UUID v4 for most applications as it's the most widely supported and provides excellent randomness without privacy concerns.
•Store UUIDs as binary (16 bytes) in databases when possible for better performance and storage efficiency.
•Always validate UUIDs when accepting them as input to prevent injection attacks and data corruption.
•Use lowercase format by default for consistency, but uppercase is also valid per RFC 4122.
•Consider UUID v1 only if you need sortable identifiers, but be aware of potential privacy implications.
•Index UUID columns properly in databases to maintain query performance despite their size.