BASE is a multidisciplinary search engine for scholarly internet resources which have been harvested from several hundred scientific repositories. Some of the indexed resources in BASE are subject to license, while most material is free available ("open access").

Google Book Search is a service from Google that searches the full text of books that Google scans, converts to text using optical character recognition, and stores in its digital database.

LIVIVO bundles scientifically relevant resources from the subjects fields medicine, health, nutrition, environmental and agricultural sciences. It provides a common search interface over various data sources, such as library catalogs, specialist bibliographic databases, full texts from journals, and quality-controlled web content. LIVIVO combines the former ZB MED search portals MEDPILOT (2003 to 2015) and GREENPILOT (2009 to 2015).

The Max Planck e-Book Index provides holdings of electronic books licensed for users in the Max Planck Society.

zbMATH Open (formerly known as Zentralblatt MATH) is the world's most complete and longest running abstracting and reviewing service in pure and applied mathematics. The MATH Database contains several million entries drawn from more than 3,500 serials and journals, and more than 1,100 book series and monographs. The entries are classified according to the Mathematics Subject Classification Scheme (MSC 2000).