The objective of this paper is to identify the factors currently taken into account for selection of vendors while outsourcing software development projects, and also to clump up such factors which make up an even more saturated segregation technique. We performed a systematic literature review wherein we took account of various research articles and boiled them down to our own conclusions. Performing a Systematic literature Review has let us put forth such factors in which previous models can be categorized and also helps in scaling the vendors to find one that suits the best for a particular project to be outsourced.