How the uuid generator works
UUID Generator creates RFC 4122 compliant Version 4 Universally Unique Identifiers (UUIDs / GUIDs). A UUID is a 128-bit identifier represented as 32 hexadecimal digits formatted into five hyphenated groups (8-4-4-4-12). Version 4 UUIDs rely on cryptographic pseudorandom number generators to virtually eliminate collision probability.
Our generator uses your browser's native `crypto.getRandomValues()` API, making the identifiers suitable for database primary keys, distributed system transaction IDs, session tokens, and mock test data.
Step-by-step instructions
- Choose whether you need a single UUID or a batch of multiple UUIDs.
- Click Generate UUIDs to instantly create fresh identifiers.
- Click Copy to clipboard to grab the generated UUIDs.
RFC 4122 UUID v4 Specification
xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx (where y is 8, 9, a, or b)122 bits of cryptographic entropy are combined with 4 bits indicating version 4 (0100) and 2 bits indicating variant 1 (10xx), yielding 2^122 (approx. 5.3 × 10^36) possible unique combinations.
Practical example
Sample UUID v4: '9b1deb4d-3b7d-4bad-9bdd-2b0d7b3dcb6d'. Note the '4' at the start of the 3rd group and '9' in the 4th group.
Frequently asked questions
Can two generated UUID v4 identifiers collide?
The probability of generating a duplicate UUID v4 is negligible. You would need to generate approximately 1 billion UUIDs per second for 85 years to reach a 50% chance of a single collision.
What is the difference between a UUID and a GUID?
GUID (Globally Unique Identifier) is Microsoft's implementation of the standard UUID specification; they are structurally identical.
Are these UUIDs generated using secure random numbers?
Yes. We use window.crypto.getRandomValues(), the browser's cryptographically secure pseudorandom number generator (CSPRNG).