Mendeley is a desktop and web program for managing and sharing research papers, discovering research data and collaborating online. It combines Mendeley Desktop, a PDF and reference management application (available for Windows, Mac and Linux) with Mendeley Web, an online social network for researchers. Mendeley requires the user to store all data on its servers. Upon registration, Mendeley provides the user with 1000 MB of free space, which is upgradeable at a cost.