The UUID Generator creates cryptographically secure UUID v4 identifiers. Generate up to 100 UUIDs at once in multiple output formats to meet different development needs. All generation happens locally in your browser for security.
What is UUID?
UUID (Universally Unique Identifier) is a 128-bit identifier designed to be unique across distributed systems. The goal is that any ID generated by anyone, anywhere will never collide. Standard UUID format is 32 hexadecimal characters in 8-4-4-4-12 pattern, like: 550e8400-e29b-41d4-a716-446655440000.
UUID Versions Explained
- UUID v1: Based on timestamp and MAC address, may leak device information.
- UUID v3: Generated from namespace and name using MD5 hash.
- UUID v4: Based on random numbers, the most commonly used version. This tool generates this version.
- UUID v5: Generated from namespace and name using SHA-1 hash.
- UUID v4 is completely random with 2^122 possible combinations, making collisions practically impossible.
Use Cases
Database Primary Keys: Using UUID as primary key avoids ID conflicts in distributed databases and supports data merging. API Request Tracking: Assign UUID to each request for log analysis and troubleshooting. File Naming: Use UUID to prevent filename conflicts, especially for upload systems. Session Identifiers: Web applications use UUIDs for user sessions that are difficult to guess.
FAQ
Q: What's the difference between UUID and GUID?
A: UUID and GUID are essentially the same thing. UUID is the general term, while GUID (Globally Unique Identifier) is Microsoft's terminology. They have identical formats and generation algorithms, and can be used interchangeably.
Q: Can UUID v4 collide?
A: Theoretically possible, but probability is extremely low. UUID v4 has 122 bits of randomness - generating a collision requires about 2.71×10^18 UUIDs. Even generating 1 billion per second would take 85 years for a possible collision. In practice, consider it won't happen.
Q: Pros and cons of UUID as database primary key?
A: Pros: Generate unique IDs without central coordination, ideal for distributed systems; Hard to guess, more secure; Can be generated offline. Cons: Takes more storage than auto-increment integers (16 bytes vs 4-8 bytes); Random UUIDs may cause B-tree index fragmentation affecting write performance (can use UUID v7 or ordered UUIDs to optimize).