Libertarianism

The Independence Institute: Colorado's Free Market Think Tank
Unlike other organizations which see government intervention as the only solution, the Independence Institute seeks to explore all alternatives, emphasizing private-sector and community-based solutions. The Independence Institute is recognized by friend and foe alike as one of the most effective organizations at setting a freedom agenda for Colorado.
https://i2i.org/
Foundation for Economic Education (FEE)
Society, Politics, Liberalism, Libertarianism - Foundation for Economic Education (FEE). Offers online education, a bookstore, and links to its seminars.
http://www.fee.org/
The Cato Institute
Society, Politics, Liberalism, Libertarianism - Cato Institute. Thousands of economic studies and articles available online, as well as streaming audio and video of institute events.
https://www.cato.org/
Atlantic Institute for Market Studies
Society, Politics, Liberalism, Libertarianism - Atlantic Institute for Market Studies. AIMS is an Atlantic Canadian libertarian institute with papers, opinions, and advice on reform.
https://www.aims.ca/
Institute of Public Affairs Australia
Australia's leading free market think tank. Promoting public policy based on individual liberty, limited government, free markets, and peaceful international relations. Hundreds of studies, articles and publications available online.
https://www.ipa.org.au/
The Centre for Independent Studies
Society, Politics, Liberalism, Libertarianism - Centre for Independent Studies. Australian institute advocating libertarian reforms through publications.
https://www.cis.org.au/
The Heartland Institute
Society, Politics, Liberalism, Libertarianism - Heartland Institute. Database of published research, primarily against environmentalist regulation.
https://www.heartland.org/