UUID Best Practices: v4, v7, and When You Should Use Each

UUIDs (Universally Unique Identifiers) are everywhere — database primary keys, request IDs, session tokens, file names. Most developers reach for UUID v4 by default, but UUID v7 is newer and better for many use cases. Here's what's changed and how to choose. What makes a UUID unique A UUID is 128 bits presented in a standardised format: xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx . The M character indicates the version (1–8), N indicates the variant. The guarantee: the probability of generating a dupli