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UUID Generator

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Generate random version 4 UUIDs (also called GUIDs) instantly - one at a time or in bulk, for developers, databases, and testing.

UUID Generator

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Version 4 UUIDs are randomly generated - practically guaranteed unique without any central coordination.

How it works

122 bits of random data, with 6 fixed bits marking it as version 4 Format: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx (y is 8, 9, a, or b)
Example

A generated UUID might look like: f47ac10b-58cc-4372-a567-0e02b2c3d479 - practically guaranteed to never collide with another randomly generated UUID.

Step-by-step guide

  1. Set how many UUIDs you need.
  2. Choose lowercase or uppercase formatting.
  3. Copy the results directly into your code, database, or configuration.

Why random UUIDs practically never collide

A version 4 UUID has 122 random bits (the remaining 6 bits are fixed to identify the version), giving roughly 5.3 undecillion (5.3 x 10^36) possible values - a number so large that generating billions of UUIDs per second for centuries would still leave collision odds effectively negligible. This is exactly why UUIDs are widely used as unique identifiers across distributed systems and databases without needing a central authority to coordinate and prevent duplicates.

Common mistakes

Assuming a UUID is sortable by creation time - version 4 UUIDs are fully random, not time-ordered, so they don't naturally sort in the order they were created.
Using UUIDs as a secret or access token - they're designed to be unique identifiers, not secrets, and shouldn't be relied on for security purposes on their own.

Frequently asked questions

What's the difference between a UUID and a GUID?

They're essentially the same concept - GUID (Globally Unique Identifier) is Microsoft's term, while UUID (Universally Unique Identifier) is the more general, cross-platform term used in the formal specification. The formats are compatible.

Why is it called "version 4" specifically?

The UUID specification defines several versions using different generation methods - version 4 is the fully random variant (the most commonly used today), while other versions incorporate timestamps or hashed namespace values instead.

Are these UUIDs generated locally, or sent to a server?

Generated entirely in your browser using a cryptographically secure random source - nothing is sent to a server.

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