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UUID / GUID Generator: Generate UUID v4 (Random UUIDs) Instantly

By Tooladex Team •
UUID GeneratorGUID GeneratorDeveloper ToolsUnique IdentifiersProgramming
UUID / GUID Generator: Generate UUID v4 (Random UUIDs) Instantly

Whether you’re building a distributed system, designing a database schema, or creating an API, you need unique identifiers that won’t collide across different systems or services.

UUIDs (Universally Unique Identifiers), also called GUIDs (Globally Unique Identifiers), solve this problem by providing identifiers that are virtually guaranteed to be unique across time and space — without requiring coordination between different systems.

The Tooladex UUID / GUID Generator makes creating UUIDs (also called GUIDs) effortless: generate single or multiple UUID v4 identifiers instantly, copy them to your clipboard with one click, and use them in your projects immediately. All generation happens entirely in your browser using cryptographic randomness — no server requests, complete privacy.

What Is a UUID?

A UUID (Universally Unique Identifier), also called a GUID (Globally Unique Identifier), is a 128-bit identifier standardized by RFC 4122. UUIDs are designed to be unique across time and space, making them ideal for distributed systems, databases, APIs, and any application requiring unique identifiers. GUID is Microsoft’s name for the same standard — UUID and GUID are effectively the same thing in practice.

UUIDs are typically represented as 32 hexadecimal digits displayed in five groups separated by hyphens:

xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx

Example UUID: 550e8400-e29b-41d4-a716-446655440000

Key Characteristics

  • 128-bit length: Provides 2^128 possible values
  • Extremely low collision probability: Approximately 1 in 2^122 (or about 1 in 5.3 × 10^36)
  • No coordination required: Different systems can generate UUIDs independently
  • Standardized format: RFC 4122 ensures compatibility across systems and languages
  • Widely supported: Libraries and support available in virtually all programming languages

Why Use UUIDs?

UUIDs offer several advantages over sequential IDs or other identifier schemes:

Distributed Systems

In distributed systems, multiple services may need to create identifiers independently. UUIDs allow each service to generate unique IDs without coordinating with other services, eliminating the need for centralized ID generation.

Benefit: Each service can generate unique identifiers without database coordination.

Database Scalability

Using UUIDs as primary keys allows databases to be sharded, replicated, or merged without ID conflicts. Unlike sequential integer IDs, UUIDs don’t require a single source of truth for ID generation.

Benefit: Databases can be distributed and scaled horizontally without ID conflicts.

Privacy & Security

UUID v4 (random UUIDs) contain no embedded information about when or where they were created. This makes them more privacy-friendly than sequential IDs that can reveal information about system usage or timing.

Benefit: Random UUIDs provide better privacy than sequential or time-based identifiers.

API Design

UUIDs make excellent resource identifiers in REST APIs because they’re opaque (don’t reveal internal structure) and globally unique. They don’t expose information about database structure or record counts.

Benefit: Better API design with opaque, unique resource identifiers.

Testing & Development

UUIDs are perfect for generating test data, mock IDs, and sample identifiers during development. You can generate UUIDs offline without database access.

Benefit: Generate test data and identifiers without database dependencies.

UUID Versions Explained

There are several UUID versions, each with different characteristics:

UUID v4 (Random UUID) — Most Common

UUID v4 is the most widely used version. It’s generated using random or pseudo-random numbers, making it ideal for most applications where uniqueness is the primary concern.

Characteristics:

  • Generated using random numbers
  • No embedded information about creation time or location
  • Extremely low collision probability
  • Most widely used and recommended for general purposes
  • Best for: Database primary keys, API identifiers, session IDs, general use

Our generator focuses on UUID v4, which is the recommended version for most use cases.

UUID v1 (Time-based UUID)

UUID v1 incorporates the current timestamp and the machine’s MAC address (or a random node ID). This allows extracting the creation time from the UUID.

Characteristics:

  • Includes timestamp information
  • Can be sorted chronologically
  • Contains MAC address (can be privacy concern)
  • Less commonly used than v4
  • Best for: Distributed systems requiring chronological ordering, logging systems

Other UUID Versions

Other UUID versions (v2, v3, v5, v6, v7, v8) exist but are less commonly used:

  • v2: DCE security version (rarely used)
  • v3: Name-based using MD5 hashing
  • v5: Name-based using SHA-1 hashing (deterministic)
  • v6-v8: Newer versions with various improvements

For most applications, UUID v4 (random UUID) is the recommended choice.

How UUID Generation Works

Our UUID Generator uses cryptographic randomness to generate UUID v4 identifiers:

Cryptographic Randomness

The generator uses the browser’s cryptographic APIs for secure random number generation:

  • Modern browsers: Uses crypto.randomUUID() API (Chrome 92+, Firefox 95+, Safari 15.4+, Edge 92+)
  • Fallback method: Uses crypto.getRandomValues() for older browsers
  • Cryptographically secure: Uses hardware random number generators when available

UUID v4 Format

UUID v4 follows the RFC 4122 specification:

  • Version field: Set to 4 (binary: 0100)
  • Variant field: Set to standard variant (binary: 10)
  • Remaining bits: Randomly generated

Client-Side Generation

All UUID generation happens entirely in your browser:

  • No server requests: UUIDs are generated locally
  • Complete privacy: Your data never leaves your device
  • Instant generation: No network latency
  • Offline capable: Works as long as the page is loaded

Tooladex UUID Generator Features

Our UUID Generator provides a comprehensive solution for generating unique identifiers:

⭐ 1. UUID v4 Generation

Generate standard-compliant UUID v4 (random UUIDs) using cryptographic randomness. All UUIDs follow RFC 4122 specification.

⭐ 2. Multiple UUID Generation

Generate 1 to 1000 UUIDs at once. Perfect for database seeding, batch processing, testing, or any scenario requiring multiple unique identifiers.

⭐ 3. Instant Generation

UUIDs are generated instantly using the browser’s cryptographic APIs. No delays, no waiting, no server round-trips.

⭐ 4. Individual Copy Buttons

Each generated UUID has its own copy button, making it easy to copy individual UUIDs to your clipboard.

⭐ 5. Copy All Functionality

Copy all generated UUIDs at once with a single click. UUIDs are copied as a newline-separated list, ready to paste into your code or database.

⭐ 6. Clean Interface

Simple, focused interface that gets out of your way. Generate UUIDs quickly without distractions.

⭐ 7. Privacy-First

All UUID generation happens entirely in your browser. Your data never leaves your device — complete privacy and security.

⭐ 8. Browser Compatible

Works in all modern browsers using native cryptographic APIs. Includes fallback methods for maximum compatibility.

Common Use Cases

Database Primary Keys

Use UUIDs as primary keys in database tables to avoid ID conflicts in distributed systems or when merging databases.

Example: PostgreSQL, MySQL, and other databases have native UUID support with optimized storage and indexing.

API Resource Identifiers

Use UUIDs as resource identifiers in REST APIs. UUIDs provide opaque, globally unique identifiers that don’t expose internal structure.

Example: /api/users/550e8400-e29b-41d4-a716-446655440000 instead of /api/users/12345

Session Management

Generate unique session IDs for user authentication and tracking. UUIDs provide sufficient entropy to prevent session hijacking.

Example: Session tokens, authentication tokens, user session identifiers

Distributed Systems

Generate unique IDs across multiple services without coordination. Each service can generate UUIDs independently.

Example: Microservices architectures, distributed databases, multi-region deployments

File Naming

Create unique filenames to avoid conflicts when storing files. UUIDs ensure unique names even when files are uploaded concurrently.

Example: User-uploaded files, generated reports, temporary files

Transaction IDs

Generate unique transaction identifiers for payment systems and financial applications. UUIDs provide sufficient uniqueness for transaction tracking.

Example: Payment processing, order IDs, invoice numbers

Testing & Development

Generate test data, mock IDs, and sample identifiers for development and testing. Generate UUIDs offline without database access.

Example: Database seeding, unit test data, mock API responses

Database Seeding

Generate multiple UUIDs for populating databases with test data. Bulk generation makes database seeding efficient.

Example: Test data generation, development environments, demo data

Resource Identifiers

Create unique identifiers for resources in web services and applications. UUIDs work across different systems and services.

Example: Resource IDs, entity identifiers, object IDs

Event Tracking

Generate unique event IDs for analytics and logging systems. UUIDs ensure event uniqueness across distributed systems.

Example: Analytics events, log entries, audit trails

Practical Examples

Here are real-world examples showing how to use UUIDs:

Example 1: Database Primary Key (PostgreSQL)

Use UUIDs as primary keys in PostgreSQL:

CREATE TABLE users (
  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  username VARCHAR(50) NOT NULL,
  email VARCHAR(100) NOT NULL,
  created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

-- Or insert with explicit UUID
INSERT INTO users (id, username, email) VALUES (
  '550e8400-e29b-41d4-a716-446655440000',
  'johndoe',
  'john@example.com'
);

Benefit: UUIDs allow database sharding and merging without ID conflicts.

Example 2: REST API Resource Identifier

Use UUIDs as resource identifiers in REST APIs:

// GET user by UUID
GET /api/users/550e8400-e29b-41d4-a716-446655440000

// POST new order with UUID
POST /api/orders
{
  "id": "7c9e6679-7425-40de-944b-e07fc1f90ae7",
  "userId": "550e8400-e29b-41d4-a716-446655440000",
  "total": 99.99,
  "items": [...]
}

// Response includes UUID
{
  "id": "7c9e6679-7425-40de-944b-e07fc1f90ae7",
  "status": "created",
  "createdAt": "2026-01-30T10:00:00Z"
}

Benefit: Opaque identifiers don’t expose database structure or record counts.

Example 3: JavaScript/Node.js Application

Generate UUIDs in JavaScript applications:

// Using crypto.randomUUID() (Node.js 14.17+, modern browsers)
const uuid = crypto.randomUUID();
console.log(uuid); // "550e8400-e29b-41d4-a716-446655440000"

// Create user object with UUID
const user = {
  id: crypto.randomUUID(),
  name: 'John Doe',
  email: 'john@example.com',
  createdAt: new Date().toISOString()
};

// Generate multiple UUIDs
const userIds = Array.from({ length: 10 }, () => crypto.randomUUID());

Benefit: Native browser/Node.js support, no external libraries needed.

Example 4: Database Seeding

Generate multiple UUIDs for database seeding:

-- Generate UUIDs for test users
INSERT INTO users (id, username, email) VALUES
  ('550e8400-e29b-41d4-a716-446655440000', 'user1', 'user1@example.com'),
  ('6ba7b810-9dad-11d1-80b4-00c04fd430c8', 'user2', 'user2@example.com'),
  ('6ba7b811-9dad-11d1-80b4-00c04fd430c8', 'user3', 'user3@example.com'),
  ('6ba7b812-9dad-11d1-80b4-00c04fd430c8', 'user4', 'user4@example.com'),
  ('6ba7b813-9dad-11d1-80b4-00c04fd430c8', 'user5', 'user5@example.com');

Benefit: Generate test data offline without database dependencies.

Example 5: Session Management

Use UUIDs for session identifiers:

// Generate session ID
const sessionId = crypto.randomUUID();

// Store session
sessions.set(sessionId, {
  userId: user.id,
  createdAt: Date.now(),
  expiresAt: Date.now() + (24 * 60 * 60 * 1000) // 24 hours
});

// Validate session
if (sessions.has(sessionId)) {
  const session = sessions.get(sessionId);
  // ... handle authenticated request
}

Benefit: Sufficient entropy to prevent session hijacking.

Best Practices

Choose the Right UUID Version

For most applications, UUID v4 (random UUID) is the recommended choice. It provides the best balance of uniqueness, privacy, and simplicity.

Consider Storage Size

UUIDs are 16 bytes (128 bits), larger than integer IDs (typically 4-8 bytes). For very large tables with millions of rows, consider the storage and indexing implications.

Tip: Many databases have optimized UUID storage and indexing (e.g., PostgreSQL’s uuid-ossp extension).

Use UUIDs Appropriately

UUIDs are ideal for:

  • Distributed systems
  • APIs and web services
  • Systems requiring offline ID generation
  • Databases that may be merged or sharded

Consider sequential IDs for:

  • Very high-volume single-database applications
  • Applications where size is critical
  • Simple CRUD applications with a single database

Database Support

Use database-native UUID support when available:

  • PostgreSQL: uuid type with gen_random_uuid() function
  • MySQL: CHAR(36) or BINARY(16) with UUID() function
  • SQL Server: uniqueidentifier type with NEWID() function
  • MongoDB: UUID support in drivers

Validation

Validate UUIDs using standard libraries or regular expressions. Most programming languages have UUID validation in standard libraries. You can also use our UUID / GUID Validator to check if UUIDs are valid, detect their version, and get detailed validation feedback.

Regex pattern for UUID v4: /^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/i

Frequently Asked Questions

What is UUID v4?

UUID v4 (version 4) is a randomly generated UUID. It’s the most commonly used UUID version and is generated using random or pseudo-random numbers. UUID v4 doesn’t contain any information about when or where it was created, making it ideal for most applications where uniqueness is the primary concern.

How unique are UUIDs?

UUID v4 has an extremely low collision probability — approximately 1 in 2^122 (or about 1 in 5.3 × 10^36). This means the chance of generating duplicate UUIDs is negligible for practical purposes. Even if you generated 1 billion UUIDs per second, it would take approximately 85 years to have a 50% chance of generating one duplicate.

Are UUIDs secure?

UUID v4 uses cryptographic randomness, making them suitable for use in security-sensitive applications. However, UUIDs themselves are not encrypted or hashed — they’re just unique identifiers. Don’t use UUIDs as security tokens or passwords. They’re designed for uniqueness, not secrecy.

Can I generate multiple UUIDs at once?

Yes! You can generate 1 to 1000 UUIDs at once. This is perfect for database seeding, batch processing, testing, or any scenario where you need multiple unique identifiers. Simply adjust the “Number of UUIDs” input and click generate.

Is my data sent to a server?

No. All UUID generation happens entirely in your browser using the browser’s cryptographic APIs. Your data never leaves your device, ensuring complete privacy and security.

What’s the difference between UUID v1 and v4?

UUID v1: Time-based UUID that includes timestamp and MAC address information. Can be sorted chronologically but contains potentially sensitive information.

UUID v4: Randomly generated UUID with no embedded information. Most widely used, recommended for general purposes, and provides better privacy since it doesn’t contain any identifying information.

Can I use UUIDs as database primary keys?

Yes! UUIDs are commonly used as primary keys in databases, especially in distributed systems. However, be aware that UUIDs are larger (16 bytes) than integer IDs (4-8 bytes) and may have performance implications for very large tables or indexes. Many databases have native UUID support with optimized storage.

How do I validate a UUID?

UUIDs follow a specific format: 32 hexadecimal digits displayed in five groups separated by hyphens: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx. You can validate UUIDs using regular expressions or UUID validation libraries. Most programming languages have UUID validation functions in their standard libraries. You can also use our UUID / GUID Validator to validate UUIDs instantly and detect their version.

Can UUIDs be sorted?

UUID v4 (random UUIDs) cannot be meaningfully sorted since they’re randomly generated. UUID v1 (time-based UUIDs) can be sorted chronologically since they contain timestamp information. If you need sortable unique IDs, consider UUID v1 or using ULIDs (which are lexicographically sortable).

UUID vs GUID?

UUID and GUID are effectively the same thing in practice: GUID is Microsoft’s name for the same standard, while UUID is the standards-based name from RFC 4122. Most “GUID generators” are just generating UUID v4 (random UUIDs) anyway. Both terms refer to the same 128-bit unique identifier format. The generator on this page produces standard UUID v4 values that work interchangeably as UUIDs or GUIDs in any system.

What browsers support UUID generation?

Modern browsers (Chrome 92+, Firefox 95+, Safari 15.4+, Edge 92+) support the native crypto.randomUUID() API. Our generator also includes a fallback method using crypto.getRandomValues() for older browsers, ensuring UUID generation works across all modern browsers.

Try the Tooladex UUID / GUID Generator

The Tooladex UUID / GUID Generator helps you:

  • Generate UUID v4 (random UUIDs) instantly
  • Create single or multiple UUIDs (1-1000 at once)
  • Copy individual UUIDs or all UUIDs with one click
  • Generate UUIDs entirely in your browser for complete privacy
  • Use cryptographic randomness for secure generation
  • Work offline once the page is loaded

Whether you’re building distributed systems, designing databases, creating APIs, generating test data, or working with any application requiring unique identifiers, this tool makes UUID generation simple and efficient.

✔ UUID v4 (random UUID) generation
✔ Generate 1-1000 UUIDs at once
✔ Individual and bulk copy functionality
✔ Instant generation using cryptographic APIs
✔ 100% client-side — complete privacy
✔ Browser compatible with fallback support
✔ Clean, focused interface
✔ RFC 4122 compliant

Try it now — and start generating unique identifiers for your projects.

UUID Generator

Generate UUID v4 (random UUIDs) instantly. Generate single or multiple UUIDs for databases, APIs, and distributed systems. Perfect for unique identifiers.

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