6. Social Science Research Network
The Social Science Research Network (SSRN) is a collection of papers from the social sciences community. The site offers more than 700,000 abstracts and more than 600,000 full-text papers.
There is not yet a specific option to search for only full-text articles, but because most of the papers on the site are free access, it is not often that you encounter a paywall. You must become a member to use the services, but registration is free and enables you to interact with other scholars around the world.
7. Public Library of Science
Public Library of Science (PLOS) is a big player in the world of open access science. Publishing seven open access journals, the nonprofit organization is committed to facilitating openness in academic research. According to the site, “all PLOS content is at the highest possible level of open access, meaning that scientific articles are immediately and freely available to anyone, anywhere.”
OpenDOAR, or the Directory of Open Access Repositories, is a comprehensive resource for finding open access journals and articles. Using Google Custom Search, OpenDOAR combs through open access repositories around the world and returns relevant research in all disciplines.
The repositories it searches through are assessed and categorized by OpenDOAR staff to ensure they meet quality standards.