http://www.uia.be

Website of the Union of International Associations which publishes the Yearbook of International Organizations. It is self-described as a non-profit, apolitical, independent, and NGO which has been ‘a pioneer in the research, monitoring and provision of information on international organizations, international associations and their global challenges since 1907’. It also contains a link directory to major organizations.

http://www.un.org/en/

Official website of the UN providing the initial point of navigation for the entire range of the organization’s functions.

http://www.crwflags.com/fotw/flags/int.html#world

Another useful directory of IOs which provides direct links to UN-linked websites as well as those of many regional organizations and NGOs.