UUID Versions
All seven UUID versions defined by RFC 4122 & RFC 9562, compared.
| Version | Method | Sortable | Collision | Use case |
|---|---|---|---|---|
| v1 | Time-based | ✕ | Legacy time-based IDs | Legacy time-based IDs |
| v3 | Namespace MD5 | ✕ | Reproducible namespaced IDs | Reproducible namespaced IDs |
| v4 | Random | ✕ | General purpose (most common) | General purpose (most common) |
| v5 | Namespace SHA-1 | ✕ | Reproducible namespaced IDs (prefer over v3) | Reproducible namespaced IDs (prefer over v3) |
| v6 | Reordered time | ✓ | Sortable time-based IDs | Sortable time-based IDs |
| v7 | Unix time + random | ✓ | Modern sortable IDs (recommended) | Modern sortable IDs (recommended) |
| v8 | Custom | — | Application-specific | Application-specific |