We aim to determine the features of four popular FOSS scanning tools, FOSSology,FOSSA, FOSSID(SCAS), and Black Duck, thereby providing references for users tochoose a proper tool for performing open-source license compliance in their projects.The sanity tests firstly verify the license detection function by using the above tools toscan the same project. We consider the number of found licenses and scanned sizes asmetrics of their accuracy. Then we generate testing samples in different programminglanguages and sizes for further comparing the scanning efficiency. The experiment datademonstrate that each tool would fit different user requirements. Thus this project couldbe considered as a definitive user guide.