The outsourcing of logistics activities has become a common practice by many companies, which implies an efficient choice of the Third-Party Logistics (3PLs) providers. A literature review on the 3PLs provider's selection problem shows that this selection is a very complex process which depends on several factors, which are often in conflict with one another, such as price, quality, service, location, technology, etc. This paper proposes a software tool using ELECTRE method for selecting the 3PLs providers. This tool incorporates various selection criteria and allows the user to introduce other criteria according to his needs. The application of our tool is demonstrated through an illustrative example.