IMF Data provides "access to macroeconomic and financial data" for over 200 countries from the International Monetary Fund. The site includes World Economic Outlook, International Financial Statistics, Global Financial Stability Report, and more.
Treaties in Force "is published annually by the Department of State to provide information on treaties and other international agreements to which the United States has become a party and which are carried on the records of the Department of State as of January 1st in its most recent publication year."
UNdata provides access to United Nations statistical databases, which contain "over 60 million data points cover a wide range of themes including Agriculture, Crime, Education, Employment, Energy, Environment, Health, HIV/AIDS, Human Development, Industry, Information and Communication Technology, National Accounts, Population, Refugees, Tourism, Trade, as well as the Millennium Development Goals indicators."
"The UNESCO Institute for Statistics (UIS) is the official and trusted source of internationally-comparable data on education, science, culture and communication." It contains cross-nationally comparable statistics on education, science, technology, and culture for over 200 countries.
The United Nations Treaty Collection "is a global portal providing on-line access to comprehensive information relating to the work of the Treaty Section (of the United Nations)."
World Bank Data & Research and World Bank Open Data are provided by The World Bank, which "is a vital source of financial and technical assistance to developing countries around the world."
The World Factbook is published by the CIA and "provides information on (a wide variety of topics and) issues for 267 world entities." Included are a number of maps, flags of the world, and time zone information.
Content adapted from https://libguides.mit.edu/c.php?g=413782&p=2819539, accessed 11 September 2018.