List of academic journal search engines

This page contains a representative list of major databases and search engines useful in an academic setting for finding and accessing articles in academic journals, or in repositories, archives, or other collections of scientific and other articles. As the distinction between a database and a search engine 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
 * bibliographic databases for information about databases giving bibliographic information about finding books and journal articles.

Note that "free" or "subscription" can refer both to the availability of the database or of the journal articles included. This has been indicated as precisely as possible in the lists below.