What is UUID v5?

Version 5 UUIDs are deterministic identifiers generated from a namespace + name using SHA-1 hash. Same inputs always produce same UUID. Unlike v4 (random), v5 is reproducible — useful when you need stable IDs across systems without coordination. Standard namespaces: DNS, URL, OID, X.500.

Tips

• Use DNS namespace for domain-based IDs
• URL namespace for web resource IDs
• Generate same UUID across servers for distributed systems
• More secure than v3 (uses SHA-1 not MD5)
• Random IDs need v4 (uuid v4 generator separately)

FAQs

v5 vs v4?

v4 is random (different every time). v5 is deterministic (same input = same output). Use v5 when you need reproducible IDs.

Is SHA-1 secure for this?

Yes — collision attacks don't affect UUID context. Could move to SHA-256 in future v8 but v5 is widely used and supported.

Can I create custom namespace?

Yes — use any UUID as namespace. Just ensure all systems use the same namespace UUID for consistency.