Selection of commercial-off-the-shelf software components (COTS components) has a growing importance in software engineering. Unfortunately, selection projects have a high risk of ending up into abandonment or yielding an incorrect selection. The use of some software engineering practices such as the definition of quality models can reduce this risk. We defined a process for COTS components selection based on the use of quality models and we started to apply it in academic and industrial cases. The need of having a tool to support this process arose and, although some tools already exist to partially support the involved activities, none of them was suitable enough. Because of this we developed DesCOTS, a software system that embraces several tools that interact to support the different activities of our process. The system has been designed taking into account not only functional concerns but also non-functional aspects such as reusability, interoperability and portability. We present in this paper the different subsystems of DesCOTS and discuss about their applicability.