Implementations of PDB Sandboxing in layers and mapping to different operating systems are described. In exemplary implementations, one or more pluggable databases (PDBs) are encapsulated on common container databases to form one or more PDB sandboxes. Encapsulating PDBs forms an isolation boundary layer configured to dynamically regulate security and isolation of the PDB sandboxes. Access by processes and resources to and from the PDBs inside respective PDB sandboxes through the isolation boundary layer, and access within PDB sandboxes, is regulated using dynamic access processes that dynamically vary access to resources and process disposed within and external to the PDB sandboxes.