DevToolkit

UUID v4 Generator

Generate UUID v4 values client-side.

About This Tool

UUID v4 is a universally unique identifier generated randomly. It's widely used for unique identifiers in databases, APIs, and distributed systems. This tool generates them locally in your browser.

What is a UUID?

A UUID (Universally Unique Identifier), also known as a GUID (Globally Unique Identifier), is a 128-bit number used to uniquely identify information in computer systems. UUIDs are designed to be unique across space and time, making them ideal for distributed systems where central coordination isn't possible.

The format is 8-4-4-4-12 hexadecimal digits separated by hyphens, like:550e8400-e29b-41d4-a716-446655440000

How to Use This UUID Generator

Basic Generation:

  1. Set the number of UUIDs you want to generate (1-100)
  2. Choose your formatting options (uppercase, hyphens)
  3. Click "Generate" to create random UUIDs
  4. Copy individual UUIDs or the entire list

Formatting Options:

  • Uppercase: Convert to uppercase letters (A-F instead of a-f)
  • Include Hyphens: Toggle the standard hyphen separators
  • Compact Format: Remove hyphens for a continuous 32-character string

Common Use Cases

  • Database Primary Keys: Generate unique IDs for database records without auto-increment conflicts
  • API Resource IDs: Create unique identifiers for REST API resources
  • Session Tokens: Generate unique session identifiers for user authentication
  • File Names: Create unique filenames to avoid conflicts in file systems
  • Distributed Systems: Generate IDs that are unique across multiple servers and databases

UUID Versions

UUID v1 (Time-based)

Based on timestamp and MAC address. Includes time information but reveals hardware details.

UUID v3 (Name-based, MD5)

Generated from a namespace and name using MD5 hash. Deterministic - same input always produces same UUID.

UUID v4 (Random)

This tool generates v4 UUIDs. Completely random, highest entropy. Most commonly used for general-purpose unique identifiers.

UUID v5 (Name-based, SHA-1)

Similar to v3 but uses SHA-1 instead of MD5. More secure but still deterministic.

Frequently Asked Questions

Q: How unique are UUIDs?

Extremely unique. With 128 bits of randomness, there are 2^128 possible UUIDs (approximately 3.4 × 10^38). The probability of collision is so low that you could generate billions per second for centuries without collision.

Q: Are UUIDs random?

v4 UUIDs are randomly generated using cryptographically secure random number generators. They're not truly random in a mathematical sense but have sufficient entropy for practical uniqueness guarantees.

Q: Should I use UUIDs as database primary keys?

It depends. UUIDs are great for distributed systems and avoiding ID conflicts, but they're larger than auto-increment integers and can impact database performance. Consider your specific use case and performance requirements.

Q: Can I generate UUIDs offline?

Yes! This tool works completely offline. Once the page loads, all generation happens in your browser using the Web Crypto API. No internet connection required after initial load.

Programming Examples

JavaScript

// Generate a single UUID
const { v4: uuidv4 } = require('uuid');
const id = uuidv4();

// Generate multiple UUIDs
const ids = Array.from({length: 10}, () => uuidv4());

Python

import uuid

# Generate a single UUID
id = uuid.uuid4()

# Generate multiple UUIDs
ids = [uuid.uuid4() for _ in range(10)]

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