BASE is one of the world's most voluminous search engines especially for academic web resources. The index contains more than 400 million records from more than 11,000 content providers. Approximately 60% of the indexed records are open access. Use the Advanced Search and check off only Open Access to limit your results to only OA content.

OAIster is a union catalog of records for open access resources. Built through harvesting from open access collections worldwide using the Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH), it includes more than 50 million records representing digital resources from more than 2,000 contributors.

Free Access to 5,806,999 Academic Articles.

Browse books, journals, and digital humanities works from university presses, scholarly societies, and independent not-for-profit academic publishers. Note that Project Muse also hosts closed content. This link will take you to open-only content.

Large multidisciplinary open access citation index of scholarly works. For articles where an open access version exists (on the publisher's website or in a repository), the HTML and PDF links (if available) will take you to the open access version of the work. Open Alex will automatically assign your first search to a particular field (title and abstract, author, or institution). You can then add additional search criteria and filters from the results page.

An open access source of unpublished preprints across the agricultural sciences.

Open access to 1,626,011 e-prints in the fields of physics, mathematics, computer science, quantitative biology, quantitative finance, statistics, electrical engineering and systems science, and economics. This database primarily houses preprints, which means that they have not gone through peer review.

The preprint server for biology, operated by Cold Spring Harbor Laboratory, a research and educational institution.

ChemRxiv is a free-to-access pre-publication platform dedicated to early research outputs in a broad range of chemistry fields.

An electronic archive for the self-archive papers in any areas of Psychology, Neuroscience, Linguistics many areas of Computer Science, and any other areas pertinent to the study of cognition.

EarthArXiv is a preprint server devoted to open scholarly communication. EarthArXiv publishes articles from all subdomains of Earth Science and related domains of planetary science.

Is a disciplinary repository for Economics and Business studies. Publications include mostly working papers, discussion papers and conference proceedings, but also journal articles and theses.

engrXiv is dedicated to the dissemination of engineering knowledge quickly and efficiently. It is operated by Open Engineering Inc.

A free online archive and distribution server for complete but unpublished manuscripts (preprints) in the medical, clinical, and related health sciences.

A free preprint service for the psychological sciences. Maintained by The Society for the Improvement of Psychological Science.

SocArXiv, open archive of the social sciences, provides a free, non-profit, open access platform for social scientists to upload working papers.

Zenodo is a free, open-access digital repository operated by CERN, developed under the European OpenAIRE program, for researchers to share digital artifacts such as research papers, datasets, and software.

The United States Government's official website for government open data. Includes Federal, State, County, and City data.

A curated collection of high quality data sets on a variety of topics such as Climate, Health, Demographics, Economy, and Pop Culture.

A comprehensive list of open data portals from around the world.

Dryad is an open data publishing platform and a community committed to the open availability and routine re-use of all research data.

World health datasets from the World Health Organization.

IEEE DataPort is a research data platform designed to make scientific data openly accessible to all and help researchers and institutions share research, manage their data, and collaborate with peers.

A collection of large data archives.

The Microdata Library is a collection of datasets from the World Bank and other international, regional and national organizations.

Research and data in the areas of climate change, demographic change, global health, food and agriculture, and energy and environment.

Pew Research Center is a nonpartisan fact tank that informs the public about the issues, attitudes and trends shaping the world. We conduct public opinion polling, demographic research, content analysis and other data-driven social science research. We do not take policy positions.

World health datasets that cover multiple countries.

The World Bank provides free and open access to a comprehensive set of data about development in countries around the globe, together with other datasets cited in the data catalog. Broader access to these data allow policymakers and advocacy groups to make better-informed decisions and measure improvements more accurately. They are also valuable tools to support research by journalists, academia and others, broadening understanding of global issues. This site is designed to make World Bank data easy to find, download, and use. All of the data found here can be used free of charge with minimal restrictions.

Search portal enables searching for open access content, including images, videos, audio, and 3D model plans, across multiple platforms. Enter search terms and choose a platform from the list at the bottom. You can then filter by CC license and content type.

This website brings together dozens of digitized copies of William Shakespeare's Comedies, Histories & Tragedies (First Folios).

Canadian archival collections of primary-source documents.

Internet Archive is a non-profit library of millions of free texts, movies, software, music, websites, and more.

Open Access collections of images and primary sources from libraries, museums, and archives around the world.

The Metropolitan Museum of Art has made 492,000 images of public-domain artworks available for free and unrestricted use.

A collection of 128,090,104 freely usable media files to which anyone can contribute.

Community-driven discovery service that indexes and provides access to scholarly, peer-reviewed open access books and helps users to find trusted open access book publishers.

A collection of nearly 5 million digitized books.

Access to 14,000 open access e-books.