This article contains a representative list of notable databases and search engines useful in an academic setting for finding and accessing articles in

academic journal An academic journal or scholarly journal is a periodical publication in which scholarship relating to a particular academic discipline is published. Academic journals serve as permanent and transparent forums for the presentation, scrutiny, and ...

institutional repositories An institutional repository is an archive for collecting, preserving, and disseminating digital copies of the intellectual output of an institution, particularly a research institution. Academics also utilize their IRs for archiving published work ...

, archives, or other collections of scientific and other articles. Databases and search engines differ substantially in terms of coverage and retrieval qualities. Users need to account for qualities and limitations of databases and search engines, especially those searching systematically for records such as in systematic reviews or meta-analyses. As the distinction between a

database In computing, a database is an organized collection of data stored and accessed electronically. Small databases can be stored on a file system, while large databases are hosted on computer clusters or cloud storage. The design of databases ...

and a

search engine A search engine is a software system designed to carry out web searches. They search the World Wide Web in a systematic way for particular information specified in a textual web search query. The search results are generally presented in a ...

is unclear for these complex document retrieval systems, see: * the general list of search engines for all-purpose search engines that can be used for academic purposes * the article about bibliographic databases for information about databases giving bibliographic information about finding books and journal articles. The terms "free", "subscription", and "free & subscription" will refer to the availability of the website as well as the journal articles used. Furthermore, some programs are only partly free (for example, accessing abstracts or a small number of items), whereas complete access is prohibited (login or institutional subscription required). The "Size" column denotes the number of documents (articles, publications, datasets, preprints) rather than the number of citations or references. The database itself should be the primary source of statistics, and if it is not accessible, the independent estimates released as journal papers should be. Notably, Google Scholar does not offer such detail, but the database's size has been calculated.

Operating services

Full-text aggregators

The main academic full-text databases are open archives or link-resolution services, although others operate under different models such as

mirroring Mirroring is the behavior in which one person subconsciously imitates the gesture, speech pattern, or attitude of another. Mirroring often occurs in social situations, particularly in the company of close friends or family, often going unnotice ...

or hybrid publishers. Such services typically provide access to full text and full-text search, but also metadata about items for which no full text is available. This list focuses on general-purpose services; OpenDOAR can be used to find thousands open-access repositories. The table is sorted by the number of works for which full-text is made available.

Metadata services

Publishers

Content by most academic publishers is indexed by CrossRef,

DOAJ The Directory of Open Access Journals (DOAJ) is a website that hosts a community-curated list of open access journals, maintained by Infrastructure Services for Open Access (IS4OA). It was launched in 2003 with 300 open access journals. The proj ...

and/or

DataCite DataCite is an international not-for-profit organization which aims to improve '' data citation'' in order to: *establish easier access to research data on the Internet *increase acceptance of research data as legitimate, citable contributions to ...

. Some publishers are also listed separately in the table below.

Services no longer operating

The following services are no longer operating; this may be because they were not updated, abandoned entirely, replaced by other, etc.

References