UUID Generator
Generate unique UUIDs v4 instantly
Frequently Asked Questions
What is UUID?
UUID (Universally Unique Identifier) is a 128-bit identifier used to uniquely identify information. Version 4 uses random numbers.
What's the difference between UUID v1 and v4?
UUID v1 uses timestamp and MAC address (can expose information). UUID v4 is completely random, being more secure and most commonly used today.
How to use UUID in databases?
UUIDs are great as primary keys in distributed systems. They avoid collisions and don't expose sequence. Use native UUID type (PostgreSQL) or CHAR(36)/BINARY(16).
Can UUIDs collide (repeat)?
The probability of UUID v4 collision is astronomically low — you would need to generate 2.71 quintillion UUIDs to have a 50% chance of repetition. In practice, it is considered impossible.
What is the UUID format?
UUID follows the format 8-4-4-4-12 (xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx), totaling 32 hexadecimal characters separated by hyphens. The "4" indicates version v4.
UUID or auto-increment — which to use as primary key?
UUID is better for distributed systems (multiple servers, microservices) as it avoids conflicts. Auto-increment is more efficient for simple local tables. UUID takes more space (16 bytes vs 4-8 bytes).