UUID v4 Generator Online
Generate cryptographically random UUID v4 identifiers instantly. Each UUID is generated using your browser's secure random number generator, ensuring true randomness.
What is UUID v4?
UUID v4 (Universally Unique Identifier version 4) is a 128-bit identifier generated using random or pseudo-random numbers. It follows the format xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx, where 4 indicates version 4 and y is constrained to 8, 9, A, or B. With 2^122 possible values, the probability of generating a duplicate is negligibly small.
UUID versions compared
UUID v1 uses MAC address + timestamp (can leak hardware info). UUID v4 uses pure randomness (most popular). UUID v5 uses namespace + name hashing (deterministic). UUID v7 (newer) uses timestamp + random (sortable). For most applications, UUID v4 is the standard choice.
Frequently Asked Questions
Can UUID v4 have collisions?
Theoretically yes, but practically no. With 2^122 possible UUIDs, you would need to generate 2.7 quintillion UUIDs to have a 50% chance of one collision. It is safe to treat them as unique.
Is UUID v4 sequential or sortable?
No. UUID v4 is purely random and not sortable by creation time. If you need time-sortable UUIDs, consider UUID v7 or ULID.