UUID Generator
Generate unique identifiers for your applications (v1, v4, v7)
About UUIDs
- • UUID v4 uses random numbers for uniqueness
- • UUID v7 generates time-sortable UUIDs with timestamps
- • UUID v1 includes timestamp and MAC address
- • UUIDs are 128-bit identifiers with very low collision probability
What is a UUID?
UUID (Universally Unique Identifier) is a 128-bit unique identifier widely used in software development. Defined by RFC 4122 standard, UUIDs allow you to create universally unique identifiers without central coordination. This feature is critical especially in distributed systems and microservice architectures.
UUIDs consist of 32 hexadecimal characters and are typically displayed separated by hyphens in 8-4-4-4-12 format (e.g., 550e8400-e29b-41d4-a716-446655440000). This format improves readability and ensures consistency across different systems. With Ko-Lay UUID Generator, you can create UUIDs in v1, v4, and v7 versions.
UUID v4 is generated using cryptographically secure random numbers. 122 bits are random, while 6 bits are reserved for version and variant information. It's the most commonly used version and ideal for scenarios requiring unpredictability and security.
UUID v7 is the next-generation UUID standard defined by RFC 9562. It contains Unix timestamp with millisecond precision and its sortable structure optimizes database performance. It's recommended as a secure alternative to UUID v1 in modern applications.
UUID v1 is generated using a 60-bit timestamp and the device's MAC address. It offers time-based sorting, but since MAC address can raise privacy concerns, UUID v7 is preferred today.
UUID Use Cases
Database Primary Key
Create unique record identifiers in distributed databases without collision risk.
API Resources
Use as resource identifiers in REST APIs to create unpredictable URLs.
File Naming
Generate unique names for uploaded files to prevent conflicts.
Session Management
Create secure, unique identifiers for user sessions and tokens.
Frequently Asked Questions
Technical Details
UUID uniqueness is based on mathematical probability. For UUID v4, there are a total of 2^122 (approximately 5.3 × 10^36) possible combinations. Even if you generate 1 billion UUIDs per second, your probability of experiencing a collision in 100 years is only 50%. Therefore, UUIDs are practically considered unique.
Ko-Lay UUID Generator uses the Web Crypto API to generate cryptographically secure random numbers. Generated UUIDs are created entirely in your browser, and no data is sent to any server. This protects your privacy and allows you to safely use it in sensitive projects.