UUID versions and identifiers
Choose UUIDs for identification, not secrecy, and understand when random or name-based versions fit the task.
Continue with UUID Generator, Hash Generator · Guides
UUIDs identify; they do not authorize
A UUID is useful as an identifier, but knowing an identifier should not grant access to a resource. Protect authorization with authentication and access checks, even when the identifier is difficult to guess.
Common choices
- v4 is random and is a practical default for new identifiers.
- v3 and v5 are name-based and repeatable for the same namespace and name.
- NIL is a reserved all-zero value and should not be treated as a unique generated ID.
References
Related tools
- UUID GeneratorGenerate and inspect UUID variants including NIL, v1, v3, v4, and v5 values locally.
- Hash GeneratorCompute supported cryptographic hashes and encodings from text input locally.