AGRIS is the International System for Agricultural Science and Technology providing access to bibliographic information on agricultural science and technology. It offers more than 8,9 million links to information produced by more than 350 data providers (which include research centers, development programs, international and national organizations) from more than 140 countries.

The Analytical Sciences Digital Library, ASDL, collects, catalogs, links and publishes peer reviewed web-based discovery materials pertinent to innovations in curricular development and supporting technical resources in the analytical sciences.

Arachne is the central Object database of the German Archaeological Institute (DAI) and the Archaeological Institute of the University of Cologne, administrated by Reinhard Foertsch. Arachne is intended to provide archaeologists and Classicists with a free internet research tool for quickly searching hundreds of thousands of records on objects and their attributes.

Open access to 1,373,168 e-prints in Physics, Mathematics, Computer Science, Quantitative Biology, Quantitative Finance, Statistics, Electrical Engineering and Systems Science, and Economics.

CiteSeerx is an evolving scientific literature digital library and search engine that has focused primarily on the literature in computer and information science.

CogPrints is an electronic archive for self-archive papers in any area of Psychology, Neuroscience, and Linguistics, and many areas of Computer Science (e.g., artificial intelligence, robotics, vison, learning, speech, neural networks), Philosophy (e.g., mind, language, knowledge, science, logic), Biology (e.g., ethology, behavioral ecology, sociobiology, behaviour genetics, evolutionary theory), Medicine (e.g., Psychiatry, Neurology, human genetics, Imaging), Anthropology (e.g., primatology, cognitive ethnology, archeology, paleontology), as well as any other portions of the physical, social and mathematical sciences that are pertinent to the study of cognition.

DOAJ is a community-curated online directory that indexes and provides access to high quality, open access, peer-reviewed journals.

EconBiz is a subject portal for economics and business studies. It offers access to free and licensed full texts on the internet.

Journal articles, reports, conference papers and other materials become indexed in ERIC through a formal review process of the journals and other content sources. Materials from approved sources under agreement are selected and indexed, and new records are added to the collection.

Europe PMC is a repository, providing access to worldwide life sciences articles, books, patents and clinical guidelines. Europe PMC provides links to relevant records in databases such as Uniprot, European Nucleotide Archive (ENA), Protein Data Bank Europe (PDBE) and BioStudies.

Isidore is a platform of search allowing the access to digital data of Humanities and Social Sciences.

Established in 2009 to comprehensively cover the arts and humanities, in 2014 JURN expanded in scope. JURN now also covers selected university full-text repositories and many additional ejournals in science, biomedical, business and law.

Lingbuzz is an article archive and community space for Linguistics.

MedlinePlus is the National Institutes of Health's Web site for patients and their families and friends. Produced by the National Library of Medicine, the world’s largest medical library, it brings you information about diseases, conditions, and wellness issues in language you can understand. MedlinePlus offers reliable, up-to-date health information, anytime, anywhere, for free.

A database maintained by the National Bureau of Economic Research with full text open access options.

Established in 1972, the National Criminal Justice Reference Service (NCJRS) is a federally funded resource offering justice and drug-related information to support research, policy, and program development worldwide.

OAIster is a union catalog of digital resources from WorldCat. It contains digital resources from open archive collections and represents multidisciplinary resources from more than 1,100 contributors worldwide. Records contain a digital object link allowing users access to the object in a single click.

OpenEdition brings together four platforms dedicated to electronic resources in the humanities and social sciences.

Paperity is the way towards more efficient scholarly communication in all research fields, from Sciences, Technology, Medicine, to Social Sciences, to Humanities and Arts. Our ultimate goal is to aggregate 100% of Open Access literature, published in any place around the world, in any field of research.

PhilArchive is the largest open access e-print archive in philosophy. Formerly known as the PhilPapers Archive, it is built on and integrated with the PhilPapers database.

PubChem is an open chemistry database at the National Institutes of Health (NIH). “Open” means that you can put your scientific data in PubChem and that others may use it.

PubMed comprises over 28 million citations for biomedical literature from MEDLINE, life science journals, and online books. PubMed citations and abstracts include the fields of biomedicine and health, covering portions of the life sciences, behavioral sciences, chemical sciences, and bioengineering.

PubPsych is a free information retrieval system for psychological resources. It offers a comprehensive and balanced selection of resources from a growing number of international databases with a European focus, covering the needs of academic and professional psychologists.

RePEc (Research Papers in Economics) is a collaborative effort of hundreds of volunteers in 96 countries to enhance the dissemination of research in Economics and related sciences.

ScienceOpen is a professional networking platform for scholars to enhance their research in the open, make an impact, and receive credit for it.

Find peer-reviewed research from the world's most trusted sources. Semantic Scholar is a free, nonprofit, academic search engine from AI2.