UUID Generator
Generate one or more UUID v4 identifiers. All generation uses cryptographically secure randomness.
What is a UUID?
A UUID (Universally Unique Identifier) is a 128-bit identifier that is unique across space and time. UUIDs are standardized by the Open Software Foundation (OSF) as part of the Distributed Computing Environment (DCE). The most common version, UUID v4, uses random numbers to generate identifiers that are statistically guaranteed to be unique without requiring a central registration authority.
A UUID v4 is typically represented as a 36-character string with five groups separated by hyphens, in the format 123e4567-e89b-12d3-a456-426614174000. Each group contains hexadecimal digits (0-9 and a-f), and the total number of possible UUID v4 values is approximately 5.3 x 10^36, which is vast enough to make collisions astronomically unlikely in practice.
How to Use This Tool
Set the number of UUIDs to generate using the Count field (1 to 100). Choose whether you want lowercase or uppercase output, and whether to include hyphens. Click Generate, and the UUIDs appear in the output area. Use Copy All to copy every generated UUID to your clipboard at once, one per line.
Common Uses for UUIDs
- Database Primary Keys: UUIDs serve as excellent primary keys because they are globally unique and do not require a central sequence counter, making them ideal for distributed databases.
- API Resource Identifiers: REST APIs often use UUIDs to identify resources, preventing sequential ID enumeration and providing collision-resistant identifiers across different API versions.
- Session Tokens: UUIDs can be used as session identifiers, though for security-critical applications, larger random tokens are recommended.
- File Names: When storing user-uploaded files, UUIDs prevent naming conflicts across different users and uploads.
- Transaction IDs: E-commerce and payment systems use UUIDs to track transactions without collisions across distributed systems.
UUID v4 vs Other Versions
UUID v1 uses the current timestamp and the host's MAC address, which means successive UUIDs can be predicted and the host can be identified. UUID v3 and v5 use namespace-based name hashing (MD5 for v3, SHA-1 for v5), producing the same UUID for the same input every time. UUID v4, which this tool generates, uses random numbers and provides the best balance of uniqueness and privacy for most applications. It is the most widely used UUID version in modern software development.