Customer Relationship Management (CRM) systems are very common in large companies. However, CRM systems are not very common in Small and Medium Enterprises (SMEs). Most SMEs do not implement CRM systems due to several reasons, such as lack of knowledge about CRM or lack of financial resources to implement CRM systems. SMEs have to start implementing Information Systems (IS) technology into their business operations in order to improve business values and gain more competitive advantage over rivals. CRM system has the potential to help improve the business value and competitive capabilities of SMEs. Given the high fixed costs of normal activity of companies, we intend to promote free and viable solutions for small and medium businesses. In this paper, we explain the reasons why SMEs do not implement CRM system and the benefits of using open source CRM system in SMEs. We also describe the functionalities of top open source CRM systems, examining the applicability of these tools in fitting the needs of SMEs.