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UUID Generator

Generate cryptographically strong RFC 4122 v4 UUIDs in bulk. All entropy comes from the Web Crypto API.

Options

UUIDs

Click “Generate” to create UUIDs

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What is a UUID?

A UUID (Universally Unique Identifier), also called a GUID, is a 128-bit identifier formatted as 32 hexadecimal digits in the pattern xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx. UUIDs are designed to be unique across all computers and all time without a central authority to coordinate assignments.

This tool generates Version 4 UUIDs, which are random (122 of the 128 bits are random, making collisions astronomically unlikely). You can generate one UUID or bulk-generate thousands at once.

How to generate UUIDs online

  1. Click Generate to create a new UUID (or set the count for bulk generation).
  2. The UUID(s) appear in the output panel.
  3. Click Copy to copy them to your clipboard.

Frequently Asked Questions

What is UUID v4?

UUID version 4 is randomly generated. 122 of its 128 bits are cryptographically random; the remaining 6 bits encode the version and variant. It is the most commonly used UUID version for general-purpose identifiers.

What is the probability of a UUID collision?

Generating 1 billion UUIDs per second for 100 years would give roughly a 50% chance of finding a single collision. For practical purposes, UUID v4 collisions are impossible.

What is the difference between UUID and GUID?

They are the same thing. UUID is the open standard (RFC 4122); GUID is Microsoft's name for the same format used in Windows and COM.

Can I use UUIDs as database primary keys?

Yes. UUIDs are excellent primary keys when you need globally unique IDs across distributed systems or want to avoid sequential (guessable) IDs. The downside is they are larger (16 bytes vs 4-8 bytes for integers) and harder to index efficiently in some databases.

What is UUID v1 vs v4?

UUID v1 is time-based and includes the host's MAC address — it is unique and sortable by creation time but leaks information about when and where it was generated. UUID v4 is random and reveals no information about its origin.