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UUID Generator

Generate unique identifiers (UUID/GUID) instantly with customizable versions and formats. Perfect for databases, APIs, and software development.

Generated
0
Version
v4
Format
Standard
Uniqueness
100%

⚙️ UUID Settings

Random (Most Common)
Timestamp-based
3

🆔 Generated UUIDs

UUIDs will be generated automatically

UUID Use Cases & Examples

Different UUID versions and formats for various development needs and applications.

🗄️ Database Primary Keys

Version 4 UUIDs for unique database record identifiers across distributed systems.

550e8400-e29b-41d4-a716-446655440000

🌐 API Request IDs

Unique request identifiers for API tracking, logging, and debugging purposes.

6ba7b810-9dad-11d1-80b4-00c04fd430c8

🔐 Session Tokens

Secure session identifiers for user authentication and session management.

f47ac10b-58cc-4372-a567-0e02b2c3d479

📁 File Names

Unique file identifiers to prevent naming conflicts in storage systems.

123e4567e89b12d3a456426614174000

What is a UUID?

A UUID (Universally Unique Identifier) is a 128-bit identifier used to uniquely identify objects, entities, or resources in computer systems. Also known as GUID (Globally Unique Identifier), UUIDs are designed to be unique across time and space without requiring a central authority.

UUID Versions Explained

Our generator supports the most commonly used UUID versions:

  • Version 1 (Time-based): Generated using timestamp and MAC address, ensuring temporal uniqueness
  • Version 4 (Random): Generated using random or pseudo-random numbers, most widely adopted

Version 4 vs Version 1

Version 4 UUIDs are preferred for most applications because they don't reveal any information about the generating system or time of creation. Version 1 UUIDs include timestamp information, which can be useful for sorting but may raise privacy concerns.

Common UUID Use Cases

UUIDs are essential in modern software development for various purposes:

  • Database Primary Keys: Unique identifiers for database records across distributed systems
  • API Request Tracking: Correlating requests and responses in microservices architecture
  • Session Management: Secure session tokens for web applications
  • File Storage: Preventing naming conflicts in cloud storage systems
  • Event Sourcing: Unique event identifiers in event-driven architectures
  • Distributed Systems: Coordinating actions across multiple servers

UUID Format Structure

A standard UUID consists of 32 hexadecimal digits displayed in groups separated by hyphens:

  • Standard format: 8-4-4-4-12 (e.g., 550e8400-e29b-41d4-a716-446655440000)
  • Without hyphens: 32 continuous hex digits (e.g., 550e8400e29b41d4a716446655440000)
  • Uppercase/Lowercase: Both are valid representations of the same UUID

UUID Uniqueness Guarantees

UUIDs provide practical uniqueness guarantees:

  • The probability of generating duplicate Version 4 UUIDs is negligibly small
  • Even generating one billion UUIDs per second for 100 years has an extremely low collision probability
  • No central authority needed to ensure uniqueness
  • Safe to use across distributed systems and different organizations

Frequently Asked Questions

Get answers to common questions about UUID generation, formats, and best practices.

What is the difference between UUID and GUID? +
UUID (Universally Unique Identifier) and GUID (Globally Unique Identifier) are essentially the same thing. GUID is the Microsoft term for UUID, but both refer to 128-bit identifiers that follow the same RFC 4122 standard. The terms have become synonymous in modern usage, with UUID being the more universal term used across different platforms and programming languages.
What's the difference between UUID v1 and v4? +
UUID v1 uses timestamp and MAC address for generation, making it time-sortable but potentially revealing system information. UUID v4 uses random numbers, providing better privacy and is the most commonly used version. V4 is recommended for most applications unless you specifically need time-ordering capabilities or can guarantee MAC address privacy.
Are UUIDs truly unique and collision-free? +
UUIDs provide practical uniqueness with astronomically low collision probability. For UUID v4, there are 5.3×10^36 possible combinations. Even generating 1 billion UUIDs per second for 100 years, the probability of collision is about 50%. For practical purposes, UUIDs can be considered unique, especially when generated with proper random number generators.
Can I use UUIDs as database primary keys? +
Yes, UUIDs make excellent primary keys, especially in distributed systems. They eliminate the need for coordination between different database instances and prevent conflicts during data merging. However, they use more storage space than auto-incrementing integers (16 bytes vs 4-8 bytes) and may impact index performance in some databases due to their random nature.
Should I use UUIDs with or without hyphens? +
Both formats are valid and represent the same UUID. Use hyphens (8-4-4-4-12 format) for human readability, API responses, and standardized string representation. Remove hyphens when you need compact storage, database optimization, or when integrating with systems that expect the 32-character format. Many APIs and libraries accept both formats automatically.
How do UUIDs compare to auto-incrementing IDs? +
UUIDs provide global uniqueness without coordination, making them ideal for distributed systems, offline generation, and data merging. Auto-incrementing IDs are smaller (4-8 bytes vs 16 bytes), faster to generate, and provide natural ordering. Choose UUIDs for distributed systems, microservices, or when merging databases. Use auto-incrementing IDs for simple applications with single databases where performance is critical.
Are UUIDs secure enough for tokens and sessions? +
UUID v4 provides good unpredictability due to random generation, but they're not designed as cryptographic tokens. For security-sensitive applications like session tokens or API keys, consider using cryptographically secure random generators, JWT tokens, or purpose-built secure token systems. UUIDs can be part of a security strategy but shouldn't be the only security mechanism.
Can UUIDs be sorted or ordered chronologically? +
UUID v1 can be time-sorted since they contain timestamp information, making them suitable for applications requiring chronological ordering. UUID v4 cannot be meaningfully sorted as they're randomly generated. If you need sortable unique identifiers, consider UUID v1, ULID (Universally Unique Lexicographically Sortable Identifier), or timestamp-prefixed UUIDs.
What is the structure and format of a UUID? +
A UUID consists of 32 hexadecimal characters (0-9, A-F) arranged in five groups: 8-4-4-4-12, separated by hyphens. The total length is 36 characters including hyphens. For example: 550e8400-e29b-41d4-a716-446655440000. The format follows RFC 4122 standard, with specific bits indicating the version and variant of the UUID.
How many UUIDs can theoretically be generated? +
There are 2^128 (about 3.4 × 10^38) theoretically possible UUIDs. For UUID v4, approximately 5.3 × 10^36 combinations are available due to reserved bits for version and variant information. This is an astronomically large number - you could generate a billion UUIDs every second for billions of years without significant risk of collision.
Can UUIDs be used in URLs and APIs safely? +
Yes, UUIDs are URL-safe and don't require encoding since they only contain hexadecimal characters and hyphens. They're particularly useful for REST APIs, resource identifiers, and situations where you need globally unique, non-guessable IDs in URLs. UUIDs prevent enumeration attacks and provide better security than sequential IDs in public APIs.
What are the performance implications of using UUIDs? +
UUIDs use more storage (16 bytes vs 4-8 bytes for integers) and can impact database index performance due to their random nature, which prevents optimal clustering. However, the benefits often outweigh costs in distributed systems. To optimize performance, consider using UUID as a secondary index alongside a sequential primary key, or use ordered UUIDs (v1) when possible.
Are UUIDs generated by this tool cryptographically secure? +
Our UUID generator uses JavaScript's built-in random number generator, which provides good randomness for most applications but isn't cryptographically secure. For security-critical applications requiring cryptographically secure UUIDs, use server-side generation with cryptographically secure random number generators (CSPRNG) or specialized libraries designed for cryptographic applications.
How should I store UUIDs in databases? +
Store UUIDs as binary(16) or specialized UUID data types when available for optimal storage and performance. Avoid storing as varchar(36) unless necessary for compatibility. Many databases (PostgreSQL, MySQL 8.0+, SQL Server) have native UUID support with optimized storage and indexing. Always use proper indexing strategies and consider the performance implications of random UUIDs on clustered indexes.
When should I use UUIDs vs other identifier schemes? +
Use UUIDs when you need: global uniqueness across systems, offline ID generation, distributed systems coordination, data merging from multiple sources, or non-sequential public identifiers for security. Use auto-incrementing integers for: single database systems, performance-critical applications, natural ordering requirements, or when storage space is constrained. Consider hybrid approaches for complex systems.

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