IUCLID is a three-tier J2EE application. This means that a client-server architecture has been applied in which the user interface, functional process logic ("business rules"), data storage and data access were developed and maintained as independent modules.

This applies especially to the distributed (network) version of IUCLID.

For the simpler stand-alone workstation version the architecture is reduced to 2-tier architecture. The program code of the servlet engine, i.e. the middle tier is executed by the client. The workstation version is limited to a single session (i.e. no multi user access).

The following diagram shows the three- and two-tier architectures of IUCLID:

In a distributed environment both http and https connections are sufficient for remote access to the central IUCLID installation. The access can be controlled by standard network mechanisms (firewall, etc.).