UUID / GUID Generator

A UUID (Universally Unique Identifier) is a 128-bit identifier standardized by RFC 4122, designed to be unique across time and space without requiring coordination or central authority. UUIDs are typically displayed as 32 hexadecimal digits in 5 groups separated by hyphens, for example: 550e8400-e29b-41d4-a716-446655440000.

The term GUID (Globally Unique Identifier) refers to the same standard but is the terminology used by Microsoft. Both UUIDs and GUIDs follow the same RFC 4122 specification and are functionally identical. They provide a way to generate unique identifiers in distributed systems without coordination between generating parties.

Our UUID generator produces UUID version 4 (random UUIDs), which use cryptographically strong random or pseudo-random numbers to ensure uniqueness. UUID v4 is the most commonly used version because it doesn't require coordination, timestamp information, or MAC addresses, making it ideal for most applications. The probability of generating duplicate UUIDs is approximately 1 in 5.3 × 10^36, making collisions virtually impossible in practice.

// Manual ID generation
const id = Date.now() + Math.random();
// Problem: Not truly unique
// Problem: Collisions possible
// Problem: Not standardized
// Problem: Not suitable for distributed systems

// UUID generation
const uuid = generateUUID();
// Result: 550e8400-e29b-41d4-a716-446655440000
// ✓ RFC 4122 compliant
// ✓ Truly unique
// ✓ Standardized format
// ✓ Works in distributed systems

UUID Versions and Use Cases

Following best practices when using UUIDs ensures optimal performance, compatibility, and reliability. Here are essential guidelines:

1. Choose the Right UUID Version

UUID v4 (random) is recommended for most use cases because it doesn't require coordination, doesn't expose system information (like MAC addresses), and provides sufficient uniqueness. Use UUID v1 (time-based) only when you need sortable, time-ordered identifiers. Use UUID v5 (name-based) when you need deterministic UUIDs from the same input.

2. Use Appropriate Database Types

When storing UUIDs in databases, use native UUID types when available (PostgreSQL has UUID type, MySQL 8.0+ supports UUID type). For databases without native UUID support, use CHAR(36) for dashed format or BINARY(16) for compact storage. Indexing UUID columns improves query performance, especially in large tables.

3. Standardize on One Format

Choose one UUID format (typically with dashes) and use it consistently throughout your application. Standard format with dashes is most readable and widely supported. Avoid mixing formats within the same system to prevent confusion and compatibility issues. Lowercase is the most common convention, but both cases work.

4. Consider Performance Implications

UUIDs are larger than auto-incrementing integers (16 bytes vs 4-8 bytes), which can impact storage and indexing. For high-traffic applications with millions of records, consider the storage overhead. However, UUIDs eliminate the need for centralized ID generation, making them essential for distributed systems where the benefits outweigh the storage costs.

5. Validate UUIDs in Your Application

Always validate UUID format in your application code before using them. Most programming languages have UUID validation libraries. Validation ensures data integrity and prevents issues from malformed identifiers. Regular expressions can also validate UUID format, but dedicated libraries are more reliable.