SSRN is a database for research from the social sciences and humanities, including 846,589 research papers from 426,107 researchers across 30 disciplines. Most of these are available for free, although you may need to sign up as a member (also free) to access some services.
Business/Economics
EconBiz
EconBiz is an excellent resource for economic and business studies. It offers the option of searching all free access journals or only open access material.
2 EconLit Run by the American Economic Association,
EconLit is a collection of more than 120 years of economic research. Here you will find plenty of reputable resources. It does require a membership, but you can get limited access to the website without one.
3 EconStor
EconStor offers more than 128,000 open access documents in the field of economics and allows you to search by author, year, document type, or collection.
4 EDGAR Search The U.S. Securities and Exchange Commission has a collection of information intended to educate investors on the conditions of the stock market. The resource is called EDGAR, and it provides access to more than 21 million findings, including full texts of filings published in the past four years.
5 IDEAS Boasting its status as "the largest bibliographic database dedicated to economics and available freely on the Internet," IDEAS indexes over 2.2 million items, more than 2 million of which can be freely downloaded.
6 Inomics Although primarily a job-search tool, this site also allows you to search for recent articles by subject. Not only can you do your research here, but you can also sign up and customize a news feed that will deliver you articles of interest.
7 National Bureau of Economic Research The National Bureau of Economic Research has compiled tons of research into an easy-to-use, searchable website. The research is conducted by over 1,400 economics university
Humanities/Social Sciences
8. Artcyclopedia This should be a go-to resource for art majors. You can search for information by artist, artwork, or location. It will then lead you to relevant articles from museums, newspapers, and other scholarly sources.
9 Digital History The Digital History website allows you to browse newspaper articles, journals, and general sources for content related to American history.
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11 Encyclopedia of Psychology The Encyclopedia of Psychology links to various resources sorted by subject. You can search by career, environment behavior relationships, organizations, paradigms and theories, people and history, publications, resources, and underlying reductionist machinery.
12 Fold3 Fold3 allows people to search U.S. military records. Though you must pay to do a thorough search of your own ancestry, you can access a fraction of their records to find general info.
13 LexisWeb Lexis provides a lot of reliably sourced content about law. Some resources can be accessed for free, but for other resources, you must purchase a membership or pay for each piece of content individually.
14 Library of AngloAmerican Culture & History The Library of Anglo-American Culture & History is a great resource for history buffs. Find what you need through its compilation of journals, newspapers, and databases. 15 Literary Encyclopedia The Literary Encyclopedia provides tons of resources on literature, history, and culture. Although you can view the entries without a membership, you do need one to view the articles in their entirety. 16 National Criminal Justice Reference Service The National Criminal Justice Reference Service provides articles and other resources focused on criminal justice and drug-related information. It is funded by the U.S. government and provides links to full-text articles whenever possible.
17 Open Library of Humanities (OLH) The mission of the Open Library of Humanities is to "support and extend open access to scholarship in the humanities." To research your topic, browse the featured journals and search for your required keywords. 4 *Items highlighted in green offer exclusively free or open access content.
18 PhilPapers PhilPapers is an index of philosophy-related journals, books, open access archives, and personal pages of academics. It is "maintained by the community of philosophers" and allows you to browse over 1,000 philosophy journals. It does have a function that allows you to search open access resources only.
19 POPLINE A free resource containing 380,000 records, POPLINE helps you seek resources related to family planning and reproductive health. Although it is free to search, access to articles does require that you pay a membership fee.
20 Psycline Psycline allows you to look for psychology and social sciences journals and articles across many databases. Although some articles are behind paywalls, others are open access.
21 PubPsych PubPsych allows users to search psychology-related resources and directs them to articles and journals. Full texts are available for most articles, but there are some you may have to purchase.
22 Social Science Research Network The Social Science Research Network (SSRN) is a collection of papers from scholars in the social sciences community. The site offers over 700,000 abstracts and over 600,000 full-text papers.
23 State Legislative Websites Directory The National Conference of State Legislatures (NCSL) gathers information from throughout the U.S. to help you cite documents such as bills and statutes.
24 The SocioWeb The SocioWeb is a search engine that guides users to sociological resources on the Internet, including websites, articles, and journals.
25 University of Oxford Text Archive
This archive is a catalog of electronic literary and linguistic resources. Although many are freely accessible, some texts have restricted access.
26 VET-Bib
VET-Bib, of the European Centre for the Development of Vocational Training, contains 80,000 references related to vocational education training. Not all articles are in English, but you can sort by language if needed.
27 WikiArc
WikiArc is a search tool that allows you to find open access documents related to archaeology
Mathematics/Computer Science
arXiv e-print Archive Run by Cornell University Library, arXiv.org provides open access to over a million e-prints in the fields of physics, mathematics, computer science, quantitative biology, quantitative finance and statistics.
CiteSeerX CiteSeerX is a computer and information science database. Here you can find links to scholarly articles and journals about related subjects.
Current Index to Statistics The Current Index to Statistics allows you to search through journals related to the fields of statistics and probability. No subscription fees are charged, but both free and paid articles are returned in searches. In each case, links to where they can be found online are provided along with the citation. CIS is set to be shut down Dec. 31, 2019, so be sure to use this resource while you can!
Computer Science Technical Reports This is a collection of computer science technical reports from the computer science department of Virginia Tech, as well as industrial and governmental research laboratories.
dblp computer science bibliography
The dblp computer science bibliography is an online reference for major computer science publications. Although it provides access to both full-text articles and those behind a paywall, you can search for only fulltext articles.
MathGuide
MathGuide is a gateway to various scholarly resources in the field of mathematics, allowing you to sort through libraries, archives, journals, open access journals, and more.
The Collection of Computer Science Bibliographies The Collection of Computer Science Bibliographies contains more than three million references. Although the site only provides bibliographic information, it includes links to PDFs or full texts on other sites where possible. There is also an option to search on Google for the full article.