What's the difference between UUID and GUID?

UUID and GUID (Globally Unique Identifier) are essentially the same thing. GUID is Microsoft's term for UUID. Both refer to the same 128-bit unique identifier format. Our generator creates standard UUID v4 identifiers.

Can I generate multiple UUIDs at once?

Yes, you can generate up to 100 UUIDs at once using our bulk generation feature. Simply select the quantity you need and click generate. All UUIDs are cryptographically secure and guaranteed to be unique.

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Free UUID Generator

Generate Version 4 UUIDs (Universally Unique Identifiers) instantly. Create random, collision-free identifiers for databases, APIs, and distributed systems.

Last Updated: 15 Jan 2026

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What is a UUID?

UUID (Universally Unique Identifier) is a 128-bit identifier standardized by RFC 4122. UUIDs are designed to be unique across time and space without requiring coordination between parties or a central registration authority. They're commonly used in distributed systems, databases, APIs, and software applications where unique identifiers are essential.

Version 4 UUIDs (the type generated by our tool) are randomly generated using cryptographically secure random number generators. They consist of 32 hexadecimal digits displayed in five groups separated by hyphens: 8-4-4-4-12 (e.g., 550e8400-e29b-41d4-a716-446655440000).

Why Use Our Free UUID Generator?

Cryptographically Secure

Our UUID generator uses cryptographically secure random number generation (crypto.randomUUID or equivalent) to ensure true randomness and uniqueness.

Bulk Generation

Generate up to 100 UUIDs at once, perfect for database seeding, test data creation, or bulk operations. Save time with instant bulk generation.

Standard Compliant

All generated UUIDs follow RFC 4122 standards and are compatible with PostgreSQL, MySQL, MongoDB, and all major databases and programming languages.

Common Use Cases for UUIDs

Database Systems

Primary Keys
Use UUIDs as primary keys in databases to avoid collisions when merging data from multiple sources or distributed systems.
Distributed Databases
UUIDs eliminate the need for centralized ID generation, making them perfect for distributed databases and microservices architectures.
Data Migration
UUIDs remain unique across database systems, making data migration and replication safer and more reliable.

API Development

REST API Resources
Use UUIDs as resource identifiers in REST APIs to prevent enumeration attacks and hide sequential IDs from users.
Session Tokens
Generate unique session identifiers, transaction IDs, or request IDs for tracking and logging purposes.
File Identifiers
Assign UUIDs to uploaded files, documents, or media assets to ensure unique filenames and prevent conflicts.

Understanding UUID Format

UUID Structure

A UUID v4 consists of 32 hexadecimal digits displayed in five groups:

550e8400-e29b-41d4-a716-446655440000

8 digits: Time low (random in v4)

4 digits: Time mid (random in v4)

4 digits: Version (4) + Time high (random)

4 digits: Variant + Clock sequence (random)

12 digits: Node ID (random)

Version 4 (Random)

Version 4 UUIDs are randomly generated using cryptographically secure random number generators. They provide the highest level of uniqueness and are the most commonly used UUID type.

Collision Resistance

With 122 bits of randomness, UUID v4 has approximately 5.3 × 10^36 possible values. The probability of generating duplicate UUIDs is astronomically low—virtually zero for practical purposes.

Frequently Asked Questions

Are UUIDs case-sensitive?

UUIDs are typically displayed in lowercase, but they're not case-sensitive. Both uppercase and lowercase representations refer to the same UUID. Our generator outputs lowercase UUIDs following standard conventions.

Can UUIDs be used in URLs?

Yes, UUIDs are URL-safe and commonly used in REST API endpoints. They're better than sequential IDs because they don't reveal information about data volume or allow enumeration attacks.

What's the performance impact of UUIDs?

UUIDs are larger (16 bytes) than integer IDs (4-8 bytes), which can impact index size and query performance. However, modern databases handle UUIDs efficiently, and the benefits often outweigh the costs.

Do UUIDs expire or become invalid?

No, UUIDs don't expire. Once generated, a UUID remains valid forever. They're designed to be permanent, unique identifiers that don't change over time.