- Wikiversity - sister project that provides information on most academic subjects
- Google Scholar  - provides a simple way to broadly search for scholarly literature
- DOAJ - multidisciplinary aggregator of Open Access journals and papers; provides free full text, advanced search and permanent URLs for all articles
- Internet Archive Scholar - fulltext search index includes over 25 million research articles and other scholarly documents preserved in the Internet Archive.
- BASE - general search engine for open archives and digital libraries, including books and academic papers
Searching for photographs by content
Resources for sourcing and searching for photographs by the content that is depicted. Though the search engines may be accessed for free, indexed images themselves may be under restricted license.
- Google Books  - Searchable archive of magazines and books (some full-text, including photograph captions and references to photographs from related articles and content).
- United States Library of Congress  - Searchable archive of historic photographs, maps, performing arts, newspapers.
- NASA Images  - Searchable archive of aeronautics, space and space exploration photographs.
- Creative Commons search and Openverse (its successor) - general search engine for Creative Commons and public domain images and more
Newspapers and news agencies
- Aljazeera  - in Arabic and English
- Asia Times Online 
- Associated Press 
- The Atlantic 
- The Australian 
- Australian Broadcasting Corporation 
- BBC Online 
- CBS News 
- CNN 
- Fox News Network 
- The Arabian Post [clarification needed]
- The Guardian 
- Haaretz 
- The Jerusalem Post 
- The New York Times [how?]
- NPR  - National Public Radio
- PBS News 
- People's Daily  - in Chinese, English, French and Spanish
- PRI  - Public Radio International
- Reuters 
- Russia Beyond the Headlines 
- Tehran Times 
- Xinhua News Agency 
- Free Newspaper Archives - comprehensive list of free, historical archives in the U.S.
- Australian Dictionary of Biography  - over 10,000 scholarly biographies of persons who were significant in Australian history
- Dictionary of Canadian Biography  - biographies devoted to people who have played an significant role in what is now Canada, who died between the years 1000 and 1930 or whose last known date of activity falls within these years
- Oxford Dictionary of National Biography  - collection of more than 57,000 specially written biographies, which describe the lives of people who shaped the history of the British Isles and beyond from the 4th century BC to the 21st century. Login is required to access, and it's not strictly free - however, if you're in the UK, entering your library card number will almost certainly get you in. Many libraries elsewhere in the world also have unrestricted access.
- Project Gutenbergs' very large collection of free, public-domain Biographies
Information and library science
- Library, Information Science & Technology Abstracts (LISTA)  - from EBSCO Publishing, the bibliographic database covers librarianship, classification, and information management, and indexes nearly 600 periodicals, plus books, research reports, and proceedings
- Internet Encyclopedia of Philosophy 
- Stanford Encyclopedia of Philosophy (web site)
- University of San Diego (web site) - Ethics Updates, resources and updates on current literature, both popular and professional, that relates to ethics
- Philosophy Dictionary of Arguments
Science, mathematics, medicine & nature
- 4researchers.org - practical "how-to" information (articles, videos, presentations, and courses) about conducting research - funding, research design, study management, dissemination, career advancement, and more.
- E!Science News  - aggregated news source from major science outlets and universities
- California Agriculture (web site) - peer-reviewed journal, reporting research, reviews and news from the University of California and its Agriculture and Natural Resources division
Biology and Medicine
- Open Biology (web site) - biology on the cellular level
- Entrez (web site) - Life Sciences search engine from the National Center for Biotechnology Information
- Global Health Observatory (GHO) (web site) - portal providing critical data and analyses for key health themes, as well as direct access to the full database, including the WHO Statistical Information System (WHOSIS)
- PubMed (web site) - comprises more than 19 million citations for biomedical literature from MEDLINE, life science journals, and online books from the United States National Library of Medicine (includes: PLOS ONE, Nutrition Journal)
- Nutrition Journal — Human nutrition journal by means of ethical guidelines
- Project Gutenberg's public domain books on Nutrition
- CalorieStar - Food Nutrition Facts including sugar content and Glycaemic Signal
- Agricultural Research Service (ARS) — chief scientific research agency within the United States Department of Agriculture, contains lots of nutrition info.
- USDA FoodData Central — contains nutrient information for many foods, including branded foods.
- Canadian Space Agency 
- EarthSky.org  — astronomy news and images, Editor-in-Chief is Deborah Byrd
- European Space Agency  - ESA
- National Aeronautics and Space Administration 
- Observatories of the Carnegie Institution for Science  — major university research institute and observatory
- Space.com  - space news
- United Nations Office for Outer Space Affairs 
- Internet Archive collection of historic NASA films, in the public domain
Technology & computer science
- Classpert - an aggregation of online courses from several providers, allowing you to find the best free ones.
- CS Academy - a free online, interactive high school computer science curriculum for Python.
- Free website Analyzer - is a free online service that collects information about domains and keywords for which they were optimized.
- Learn to Code - gitconnected.com - coding courses and tutorials ranked by developers.
- NASA Technical Reports Server (NTRS) - resource for students, educators, researchers, and the public for access to NASA's current and historical technical literature since it was first released in 1994.
- The Association for History and Computing - organisation dedicated to the use of computers in historical research.
- Website Safety and Reputation Analyzer - a free tool able to analyze websites reputation and show safety information.
- Website Social Media Analyzer - a free tool able to analyze websites features, social media impact and audience.
- Ants Toolbox - Some of the best tutorials from all over the Internet, curated by the community for all.
- American Enterprise Institute: private, conservative, not-for-profit institution dedicated to research and education on issues of government, politics, economics, and social welfare.
- Fernand Braudel Center: the Study of Economies, Historical Systems, and Civilizations.
- Glossary of Selected Social Science Computing Terms and Social Science Data Terms
- Inter-university Consortium for Political and Social Research: free access for general social survey and national election survey.
- National Geographic Society 
- OECD: Economic, social, and infrastructure data on industrialized countries.
- OurEnergyPolicy.org Resource Library: free online energy policy database.
- The Overseas Young Chinese Forum (OYCF): "The Overseas Young Chinese Forum (OYCF) is established for overseas young Chinese to exchange their views on social, economic, political and cultural issues concerning China and to develop common aspirations through regular discussions."
- World-Systems Archive
- World Values Survey : "The World Values Survey is a worldwide investigation of sociocultural and political change. It has carried out representative national surveys of the basic values and beliefs of publics in more than 65 societies on all six inhabited continents, containing almost 80 percent of the world's population."
- United Nations Human Development Report Office
- ALLBUS Data Service: online archive of German General Social Survey data. Free download - for scientific purposes - of high quality data on attitudes, behavior, and social structure in Germany.
- Project Gutenberg's shelf of historic, public domain Anthropology Books
- Library of Congress Resource Links on Anthropology
- OpenCulture, an extensive collection of varied works of many different mediums
- Transparent Blogs, a large collection of various blogs about language and language culture
- The Economist
- Index of Economic Freedom: from The Heritage Foundation/Wall Street Journal.
- International Monetary Fund: IMF research and links to World Economic Outlook.
- Review of Radical Political Economics: "The Review of Radical Political Economics (RRPE) publishes articles on radical political economic theory and applied analysis from a wide variety of theoretical traditions: Marxist, institutionalist, post Keynesian, and feminist. RRPE is published by Sage Publications."
- UNDP World Income Inequality Database
- UN Food and Agriculture Organization (FAO) FAOSTAT International data on food production, land use, nutrition.
- World Bank: World Development Indicators database.
- Economics Dictionary of Arguments
Geography, places and travel
- BBC News: Country Profiles - includes audio and video clips
- The Canadian Encyclopedia  (also in French)
- ELDIS: Country and Regional Profiles - a family of knowledge services from the Institute of Development Studies, Sussex
- Eurostat  - statistics on European Union countries
- Federal Research Division: Country Studies - from the Library of Congress, published between 1988 and 1998, information on some countries may no longer be up to date
- The World Factbook (web site) - published by the Central Intelligence Agency of the U.S.
- Wikibooks: World History from Wikibooks, a Wikimedia Foundation project
- EuroDocs: Online Sources for European History: Wiki collection of primary source historical records from Western Europe, hosted by the Harold B. Lee Library at Brigham Young University.
- Talessman's Atlas of World History: Collection of world history maps ranging from ancient to modern times, by amateur historian Thomas Lessman
- The Historical Atlas of South Asia by Joseph Schwartzberg.
- Euratlas historical maps of Europe.
- National, State & Local Newspaper Archives - Collection of free newspaper archives in the United States, from the XooxleAnswers professional online research service.
- The History Guide - Material for high school (particularly AP European History) and undergraduate students. Includes lectures on Ancient and Medieval European History, Early Modern European History, Modern European Intellectual History, and 20th Century Europe
- Lectures in Medieval History - Lecture notes by Dr. Lynn H. Nelson, Professor Emeritus of Medieval History at the University of Kansas.
- African Court of Justice  - African Union
- Coalition for the International Criminal Court 
- Amnesty International: human rights.
- European Union law 
- Human Rights Watch
- International Court of Justice  - (ICJ) United Nations' judicial body
- International Criminal Court  - ICC is in Hague, Netherlands governed by the Rome Statute
- Law Library of Congress  - United States Internet Law Library of Congress
- Adam Carr's Election Archive: User:Adam Carr maintains the world's largest online archive of election statistics from every democratic country in the world.
- Reports and publications of the Brookings Institution, public policy think tank in Washington, D.C.
- Reports and publications of the Cato Institute, public policy think-tank headquartered in Washington, D.C.
- Reports and publications of the Center for American Progress, public policy think tank in Washington, D.C.
- EULib: large, searchable collection of official European Union news and documents.
- Foreign Affairs: periodical published by the Council on Foreign Relations.
- Foreign Policy: a leading quarterly of international affairs.
- Glossary of Political Economy Terms
- Hoover Institution: "a public policy research center devoted to advanced study of politics, economics, and political economy—both domestic and foreign—as well as international affairs."
- The Jamestown Foundation "The Jamestown Foundation's mission is to contribute to U.S. understanding of its strategic adversaries that pose a threat to democracy and freedom."
- : Kennan Institute for Advanced Russian Studies, Woodrow Wilson Center: think-tank on political, social, and economic issues affecting Russia and other successor states to the Soviet Union.
- Marxists Internet Archive - Collection of primary source documents
- Monthly Review: independent socialist journal.
- New Left Review: a key journal of the international Left.
- Paul Hensel's International Relations Data Site
- The Socialist Register
- Politics Dictionary of Arguments
- Psychology's Feminist Voices (web site) - Collection of first-hand accounts of feminist psychologists (videos, interviews, profiles)
- Psychology Dictionary of Arguments
- The Catholic Encyclopedia
- Goettingen Register of Electronic Texts in Indian Languages (ancient and medieval Hindu, Buddhist and Jain texts)
- Internet Sacred Text Archive
- The British Library's complete collection of sacred texts
- Project Gutenberg's extensive shelf of historic, public domain Religious Texts
- Synod Commission for Monasteries of Ukrainian Orthodox Church
- Project Gutenberg's public domain Sociology books
- Socius — Asanet.org page • Main page on SagePub, go here to access the journal's contents — continuously-publishing open-access scholarly journal covering sociology. Published by the American Sociological Association. Asserted to be great for content relating to recent controversies.
- Art UK, online gallery of art pieces curated by the UK government 
- Internet Archive, an extensive collection of varied works of many different mediums
- MoMA, online gallery of art pieces curated by the Museum of Modern Art 
- American College of Sports Medicine  - American Collge of Sports Medicine
- ESPN 
- Free Internet Chess Server
- the Kinesiology Network  - the Kinesiology Network
- LA84 Foundation  - digital resources include academic journals, scholarly books, popular sports magazines of the late nineteenth and early twentieth centuries, and an extensive offering of Olympic publications
- NBC Sports  - has a history of broadcasting professional sports, including Olympics
- Sports Dietitians Australia  - sports nutrition
- Sports Illustrated 
- Classical Net  - Classical Music Information and Reviews
- All Music  - Reviews and Biographies
- Rotten Tomatoes  Critic's reviews, news, budget figures
- Academy Awards  Academy of Motion Picture Arts and Sciences database
- BAFTA  British Academy of Film and Television Arts
- Wikipedia:Advanced source searching
- Wikipedia:Reliable sources/Noticeboard
- Wikipedia:WikiProject Resource Exchange - a project where Wikipedians offer to search in their resources for the reference that you are looking for
- Wiktionary:Wiktionary:Other dictionaries on the Web