UUID Generator

What is a UUID?

A UUID (Universally Unique Identifier) is a 128-bit identifier that is guaranteed to be unique across space and time. UUIDs are formatted as 32 hexadecimal digits displayed in five groups separated by hyphens: 8-4-4-4-12. They are widely used as primary keys in databases, session identifiers, correlation IDs in distributed systems, and anywhere a unique identifier is needed without central coordination.

UUID v4 Explained

This tool generates UUID version 4, which uses cryptographically secure random numbers. Version 4 UUIDs have a "4" in the version position (the 13th character) and a variant indicator in the 17th character. With 122 random bits, the probability of generating a duplicate is astronomically low — you would need to generate about 2.71 quintillion UUIDs to have a 50% chance of collision.

UUID vs Auto-Increment IDs

Unlike sequential auto-increment IDs, UUIDs can be generated on any client without database coordination. This makes them ideal for distributed systems, offline-first apps, and microservices. The tradeoff is size (36 characters vs a simple integer) and reduced database index performance for very large tables.

Common Use Cases

• Database primary keys in distributed systems
• Session tokens and API request IDs
• File naming to avoid collisions
• Tracking events across microservices