UUID Generator

Generate random UUID v4 identifiers instantly. Bulk generate up to 100 at a time with formatting options.

About the UUID Generator

A UUID (Universally Unique Identifier), also known as a GUID (Globally Unique Identifier), is a 128-bit identifier that is designed to be unique across all devices and time without requiring a central registration authority. This tool generates version 4 UUIDs, which are based on random numbers and are the most commonly used variant in modern software development.

UUID v4 identifiers follow the format xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx, where x is any hexadecimal digit and y is one of 8, 9, a, or b. The 4 in the third group indicates the UUID version, while the leading bits of the fourth group indicate the variant. This tool uses the browser's built-in crypto.getRandomValues() API for cryptographically strong random number generation, ensuring high-quality randomness.

How to Use This Tool

Click Generate UUID to create one or more UUIDs. Adjust the Quantity field (1–100) to bulk-generate multiple UUIDs at once. Enable Uppercase to output UUIDs in capital letters (e.g., A1B2C3D4-...), or enable Remove hyphens to get compact 32-character strings. Use Copy All to copy every generated UUID to your clipboard at once, separated by newlines.

Common Use Cases

  • Database primary keys: Many databases use UUIDs instead of auto-incrementing integers to avoid collisions in distributed systems.
  • API request IDs: Attach a UUID to each API request for tracing and logging across microservices.
  • Session tokens: Generate unique session identifiers for user authentication.
  • File naming: Use UUIDs to create unique filenames that won't collide when uploaded by different users.
  • Testing and development: Quickly generate test data with unique identifiers.

Technical Details

The probability of generating two identical UUID v4 values is astronomically low — roughly 1 in 2122 (about 5.3 × 1036). To put that in perspective, you would need to generate approximately 2.71 quintillion UUIDs to have a 50% chance of a single collision. This makes UUIDs safe for use as unique identifiers in virtually any application without coordination between generating systems. All generation happens entirely in your browser — no network requests are made and no data leaves your device.