The concept of network slicing is gaining a lot of interest and being under notable discussion within SDOs such as 3GPP, NGMN, ETSI and 5G Americas. A Network Slice is end-to-end service composed by a set of network functions, and the resources to run these network functions, forming a complete instantiated logical network, which meets certain network characteristics.In this paper, we provide an overview of the design and development of a network slice manager component inside the SONATA Service Platform. The proposed component is able to align with ETSI NFV and 3GPP models.