What is a UUID?
A UUID (Universally Unique Identifier), also called a GUID (Globally Unique Identifier), is a 128-bit identifier formatted as a string of hexadecimal digits grouped by hyphens — for example: 550e8400-e29b-41d4-a716-446655440000. The “universally unique” part means that generating one gives you an ID that is, for all practical purposes, unique across the entire world — no central registry required.
UUIDs are widely used in software to identify records in databases, track sessions, name files, and connect data across different systems without risking collisions. Version 4 UUIDs (v4) are generated randomly, making them unpredictable and safe to use in public-facing contexts.
What Does This Tool Do?
This tool generates one or more version 4 UUIDs instantly. You can copy a single UUID or generate a batch. All generation happens locally in your browser using a cryptographically secure random number generator.
How to Use This Tool
- Click Generate to create a new UUID.
- Use the copy button to copy it to your clipboard.
- Generate multiple UUIDs at once if you need a batch.
Common Use Cases
- Database primary keys: Use UUIDs as unique IDs for database records to avoid sequential ID guessing.
- File naming: Give uploaded files unique names to prevent overwrites.
- Testing and mocking: Need fake but realistic IDs for test data? UUIDs are the standard choice.
- Distributed systems: Generate IDs on the client side without needing a server to assign them.
Frequently Asked Questions
Are UUID v4 values truly unique?
With 2¹²² possible values (about 5.3 × 10³⁶), the probability of generating the same UUID twice is astronomically small. For all practical purposes, they are unique.
Is there a difference between UUID and GUID?
The terms refer to the same concept. UUID is the standard term (from RFC 4122); GUID is Microsoft’s name for the same thing.
Is my data private?
UUIDs are generated entirely in your browser using the Web Crypto API. No data is sent to any server.