As the quantity of data is increasing maintaining the data in one place becomes difficult. In order to manage the data of researchers many open source software are available to have all the data in one organised place. These are referred to as online reference or citation management software. By automating the data one can gather, manage, and cite online references and these reference tools facilitates a more efficient research process. There are many reference tools available which are open source. Of which i am discussing two reference tools Zotero and Mendeley.