UUID Generator
Generate random UUID v4 strings instantly with custom formatting options.
What is a UUID?
A UUID (Universally Unique Identifier) is a 128-bit identifier used to uniquely identify objects in computer systems. UUIDs are designed to be unique across both space and time, making them ideal for database keys, session tokens, and distributed systems.
UUID Version 4
This tool generates Version 4 UUIDs, which are created from random (or pseudo-random) numbers. A v4 UUID follows this format:
xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx
Where x is a random hexadecimal digit and y is one of 8, 9, A, or B. The "4" in the third group indicates the version, and the "y" value indicates the variant.
When to Use UUIDs
- Database primary keys - Avoid conflicts in distributed databases
- API tokens and session IDs - Generate unique identifiers for authentication
- File naming - Create unique filenames to prevent collisions
- Testing - Generate test data for development environments
- Microservices - Unique request tracing across services
Frequently Asked Questions
How unique is a UUID v4?
With 122 bits of randomness (out of 128 total), the probability of two randomly generated UUIDs colliding is approximately 1 in 2^122, which is effectively zero for all practical purposes.
Are these UUIDs cryptographically secure?
Yes. This tool uses crypto.getRandomValues(), which provides cryptographically secure random numbers via the browser's Web Crypto API.
Can I use UUIDs as database keys?
Yes. UUIDs are commonly used as primary keys in databases. They work particularly well in distributed systems where auto-incrementing IDs could cause conflicts.
What is the difference between with and without hyphens?
With hyphens: 550e8400-e29b-41d4-a716-446655440000. Without hyphens: 550e8400e29b41d4a716446655440000. Both represent the same UUID; the format is just different.