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UUID Generator

Generate cryptographically random UUID v4 identifiers instantly — single or bulk

Reference UUIDs
Nil UUID (all zeros) 00000000-0000-0000-0000-000000000000
Max UUID (all ones) ffffffff-ffff-ffff-ffff-ffffffffffff

What Is a UUID?

A UUID (Universally Unique Identifier), also known as a GUID (Globally Unique Identifier) in Microsoft ecosystems, is a 128-bit identifier that is designed to be unique across all devices, databases, and systems worldwide without requiring a central authority. UUIDs are represented as 32 hexadecimal characters displayed in five groups separated by hyphens, following the pattern xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx. The total number of possible UUID v4 values is approximately 5.3 × 1036, making the probability of generating two identical UUIDs astronomically small — about 1 in 2122.

UUID Versions Explained

There are several UUID versions, each with different generation methods. UUID v1 uses the current timestamp and the MAC address of the generating device, which means it's unique but reveals information about when and where it was created. UUID v4 (what this tool generates) uses cryptographically strong random numbers, making it the most widely used version for general-purpose applications since it reveals no information about its origin. UUID v7 is the newest version, combining a Unix timestamp with random data to create time-ordered UUIDs that are ideal for database indexing while maintaining uniqueness.

How to Use This UUID Generator

Click the "Generate New UUID" button or simply reload the tool to get a fresh UUID v4. Use the Uppercase toggle to switch between lowercase and uppercase hex characters. Enable No hyphens to get a compact 32-character string without dashes. For bulk generation, enter a count between 1 and 100 and click "Generate Bulk" to create multiple UUIDs at once. Every UUID is generated using crypto.getRandomValues(), the browser's cryptographically secure random number generator.

Common Use Cases

  • Database primary keys: UUIDs eliminate conflicts when merging databases from different servers, making them ideal for distributed systems and microservices architectures.
  • API resource identifiers: Using UUIDs in API URLs (/users/550e8400-e29b-41d4-a716-446655440000) prevents enumeration attacks that sequential IDs enable.
  • Session tokens: UUID v4's randomness makes them suitable for session identifiers where unpredictability is essential.
  • File naming: Generate unique filenames for uploads to prevent collisions without checking existing files.
  • Distributed systems: Multiple nodes can independently generate identifiers without coordination, eliminating the bottleneck of a central ID server.