Understanding UUID Versions: v1, v4, and v5

UUIDs come in different "versions" defined by RFC 4122.

Version 1 (Time-based)

Generated using the current time and the computer's MAC address. Guaranteed unique, but leaks the creation time and the machine's identity.

Version 4 (Random)

Generated using random numbers. This is the most common version and what most people mean when they say "UUID." The chance of collision is astronomically low.

Version 5 (Namespace-based)

Generated by hashing a namespace identifier and a name. Deterministic: the same input always yields the same UUID.

Our UUID Generator defaults to v4 as it's the best choice for general use.