Learn More About UUIDs
Understand UUID versions and when to use each:
Online UUID / GUID Generator (v4)
Generate random UUIDs (Universally Unique Identifiers) and GUIDs instantly. Create single or bulk UUID v4 strings for your database, application, or API. Fast, free, and secure.
How It Works
Our tool generates Version 4 UUIDs, which are created using cryptographically secure random numbers. A UUID is a 128-bit number represented as a 36-character alphanumeric string, ensuring a near-zero probability of collision.
Common Use Cases
- Generating unique primary keys for database records (SQL or NoSQL)
- Creating unique session IDs or transaction IDs for web applications
- Generating bulk GUIDs for software testing and mock data creation
- Assigning unique identifiers to uploaded files to prevent naming conflicts
Frequently Asked Questions
UUID (Universally Unique Identifier) and GUID (Globally Unique Identifier) are essentially the same thing. GUID is simply the term used by Microsoft, while UUID is the standard term used by the rest of the tech industry.
UUID Version 4 is generated using random numbers, unlike Version 1 which uses MAC addresses and timestamps. V4 is the most common type of UUID used in modern software development due to its privacy and randomness.
While theoretically possible, the probability of generating two identical v4 UUIDs is astronomically low. You would need to generate 1 billion UUIDs per second for 85 years to have a 50% chance of a single collision.
UUID v1 includes a timestamp and MAC address, making it time-sortable but potentially revealing device info. UUID v4 is purely random, offering better privacy and no ordering.
While theoretically possible, the probability is astronomically low. With 122 random bits, you'd need to generate about 2.71 quintillion UUIDs to have a 50% chance of a collision.
No, UUIDs are case-insensitive per RFC 4122. '550e8400-E29B-41d4-A716-446655440000' and '550e8400-e29b-41d4-a716-446655440000' are the same UUID.
GUID (Globally Unique Identifier) is Microsoft's term for UUID. They are functionally identical — both follow the same RFC 4122 specification.
Yes, UUIDs are commonly used as primary keys. They enable distributed ID generation without a central authority. However, consider UUID v7 for time-sorted keys.