🆔 UUID Generator

Generate universally unique identifiers (UUID v4) instantly

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About UUIDs

UUID Version 4: Randomly generated 128-bit identifiers

Format: 8-4-4-4-12 hexadecimal digits (36 characters total)

Uniqueness: Extremely low probability of collision (~1 in 5.3 × 10³⁶)

Use Cases: Database primary keys, session IDs, unique filenames, API tokens

Example formats:
  • • Standard: 550e8400-e29b-41d4-a716-446655440000
  • • Uppercase: 550E8400-E29B-41D4-A716-446655440000
  • • No hyphens: 550e8400e29b41d4a716446655440000

What is a UUID?

A UUID (Universally Unique Identifier) is a 128-bit identifier used to uniquely identify information in computer systems. UUIDs are designed to be unique across both space and time, meaning no two UUIDs should ever be the same, even when generated on different computers at different times.

UUID Version 4: Our generator creates UUID v4, which uses random or pseudo-random numbers. This version is the most commonly used because it requires no synchronization between systems and has an extremely low probability of duplication.

Format Structure: A standard UUID contains 32 hexadecimal digits displayed in five groups separated by hyphens: 8-4-4-4-12 characters (36 total including hyphens).

When to Use UUIDs

Database Development

  • • Primary keys for distributed databases
  • • Unique record identifiers
  • • Session tokens and user IDs
  • • Avoiding auto-increment conflicts

API Development

  • • REST API resource identifiers
  • • Request tracking and correlation
  • • Authentication tokens
  • • Message queue identifiers

File Management

  • • Unique filename generation
  • • Document version tracking
  • • Cloud storage identifiers
  • • Cache busting parameters

System Integration

  • • Microservice communication
  • • Transaction identifiers
  • • Event sourcing IDs
  • • Distributed system coordination

Technical Specifications

UUID v4 Structure

xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx
• x: Random hexadecimal digit (0-9, a-f)
• 4: UUID version identifier (always 4 for v4)
• y: Random digit with first two bits set to 10 (8, 9, a, or b)

Uniqueness Probability

• Total possible UUIDs: 2^122 ≈ 5.3 × 10^36
• Collision probability: Effectively zero for practical purposes
• Safe generation rate: Billions per second without concern

UUID Best Practices

Do

  • • Use lowercase for consistency
  • • Include hyphens for readability
  • • Store as strings or binary in databases
  • • Use for distributed systems
  • • Generate client-side when possible

Avoid

  • • Using UUIDs for sorting by creation time
  • • Exposing UUIDs in URLs unnecessarily
  • • Mixing UUID formats in same system
  • • Using for small, single-server applications
  • • Assuming chronological ordering

Programming Examples

JavaScript

// Generate UUID v4
const uuid = crypto.randomUUID();
console.log(uuid); // Output: 123e4567-e89b-12d3-a456-426614174000

Python

import uuid
new_uuid = str(uuid.uuid4())
print(new_uuid) # Output: 123e4567-e89b-12d3-a456-426614174000

PHP

// Using ramsey/uuid package
$uuid = Uuid::uuid4();
echo $uuid->toString(); // Output: 123e4567-e89b-12d3-a456-426614174000