Global Pulse collaborated with Data2X and the University of Leiden to develop and prototype a tool to infer the sex of users. The tool automates the process of looking up public information from Twitter profiles, in particular the user name and profile picture. Using open source software, the tool analyses user names from a built-in database of predefined names (from sources such as official statistics) that contain gender information. Cite as: UN Global Pulse, 'Sex-Disaggregation of Social Media Posts,' Big Data Tools Series, no. 3, 2016