UUID Generator
Generate cryptographically random UUID v4 identifiers. Generate one or up to 100 at a time.
Single UUID v4
Related tools
About UUID Generation
A UUID (Universally Unique Identifier) is a 128-bit identifier standardized in RFC 4122. UUIDs are designed to be unique across systems and time without requiring a central authority to coordinate assignments. They are widely used as primary keys in databases, entity identifiers in distributed systems, correlation IDs in logging, and anywhere a unique identifier is needed without coordination.
UUID v4
UUID v4 is generated from random (or pseudo-random) bits. 122 of the 128 bits are random; the remaining 6 bits encode the version and variant. The format is: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx where 4 is the version and y is one of 8, 9, a, or b (the variant bits).
Collision probability
With 122 random bits, the probability of generating a duplicate UUID is astronomically low. You would need to generate approximately 2.7 × 10¹⁸ UUIDs before reaching a 50% chance of a single collision — well beyond any practical use case.
Privacy
UUIDs are generated using your browser's built-in crypto.randomUUID() API. Nothing is sent to any server. Learn more about how Dev-Utilities handles privacy.