- Web of Science
- Scopus
- MathSciNet
- zbMATH-ZentralblattMATH
- arXiv
- INSPIRE (high-energy physics)
- ADS - the NASA Astrophysics Data System
- PubMed: National Library of Medicine (USA) : a database of more than 30 million citations and abstracts to the biomedical literature literature
- PubMed Central (PMC) : a digital archive of full text biomedical literature
- bioRxiv : preprint server for biology
- ClinicalTrials.gov : U.S. National Library of Medicine.: a registry and results database for clinical trials
- Database of Genotypes and Phenotypes : U.S. National Library of Medicine.: data from studies of the relationship between variations in genotypes and the expression of disease
- MedlinePlus : U.S. National Library of Medicine: consumer-friendly information from trusted sources on more than 1000 diseases
- Dimensions ; free version of Dimensions provides openly-available search and metrics for more than 100 million publications. With an institutional license to Dimensions Analytics, the content they can access expands to cover grants, clinical trials, patents, datasets and policy documents,
- SISSA Open Science : SISSA preprints, SISSA proceedings and SISSA lectures notes
- SISSA Articles acquisition (available only through SISSA network).
- PLEIADI : Portale per la letteratura scientifica elettronica italiana su Archvi aperti e Depositi Istituzionali
- DART-Europe : access to European research digital PhD theses
- Preprints in Technology Research ( TechRxiv.org, is a free preprints repository of the IEEE in electrical engineering, computer science, and related technologies
- Earth Science preprints
- Engineering preprints archive
- Open archive for social sciences
- Cogprints : preprints in cognitive science
- Preprint service for the psychological sciences
- Preprints and post-print repository of scholarly legal content
- International Nuclear Information System (INIS-IAEA)
- PubChem
- External preprint archives