UUID vs GUID: Complete Guide to Unique Identifiers
Learn the difference between UUID and GUID, understand UUID versions, and discover when to use unique identifiers in your applications.
UUIDs (Universally Unique Identifiers) and GUIDs (Globally Unique Identifiers) are 128-bit numbers used to uniquely identify information in computer systems without requiring a central authority.
What is This?
A UUID is a 128-bit number represented as 32 hexadecimal digits, displayed in five groups separated by hyphens (e.g., 550e8400-e29b-41d4-a716-446655440000). GUID is Microsoft's implementation of the UUID standard. They are functionally identical and can be used interchangeably.
How to Generate UUIDs
- Open our UUID Generator tool
- Select the UUID version (v1, v4, v5)
- Click "Generate UUID" to create a unique identifier
- Copy the UUID for use in your application
- Generate multiple UUIDs for batch operations
Benefits
- No Central Authority: Generate unique IDs without a database
- Collision Resistant: Probability of collision is virtually zero
- Distributed Systems: Perfect for microservices and distributed databases
- Privacy: Don't reveal sequential information like auto-increment IDs
- Portable: Work across different systems and platforms
Common Use Cases
Database Primary Keys
Use UUIDs as primary keys in distributed databases where multiple servers generate records simultaneously. Unlike auto-increment IDs, UUIDs prevent ID conflicts during database merges or replication.
API Request IDs
Track API requests across microservices with unique request IDs. UUIDs make it easy to trace requests through distributed logging systems without coordination between services.
File Names
Generate unique file names for user uploads to prevent name conflicts. UUIDs ensure that files from different users never overwrite each other, even with identical original names.
Session Tokens
Create unpredictable session identifiers for web applications. UUIDs provide cryptographically strong randomness that makes session hijacking extremely difficult.
Tips & Tricks
- Use UUID v4 for most cases: Random UUIDs (v4) are best for general-purpose unique identifiers
- Consider UUID v1 for time-based: If you need time-ordering, UUID v1 includes timestamp information
- Index properly: In databases, consider using UUID as primary key with proper indexing strategies
- Store as binary: Store UUIDs as 128-bit binary in databases for better performance than strings
- Avoid in URLs: UUIDs make long, ugly URLs - consider shorter alternatives for public URLs
Conclusion
UUIDs are essential tools for modern distributed systems, providing collision-resistant unique identifiers without central coordination. Whether you're building microservices, distributed databases, or need unique file names, UUIDs offer a reliable solution. Try our free UUID generator to create v1, v4, or v5 UUIDs instantly.