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").

Digi20 concentrates on the digitalization of monographs published in the second half of the 20th century, predominantly in the field of humanities and social sciences. In the first phase of the project, approx. 4,700 titles of programme segments of the publishers Vandenhoeck & Ruprecht, Wilhelm Fink / Ferdinand Schöningh as well as Otto Sagner were digitized. In a second phase, further approx. 1,750 titles are being included till 2014 by consecutively digitizing all monographs up to a defined ‘Moving Wall’ of three to five years to the current year of publication.

The primary aim of DOAB is to increase discoverability of Open Access books. Academic publishers are invited to provide metadata of their Open Access books to DOAB. An overview of participating publisher can be found here.

The DOAJ service lists toll-free, quality controlled, scientific and scholarly journals. It generally aims at covering all subjects and languages. The DOAJ Articles Search is restricted to those journals the publisher has supplied article metadata for.

Edition Open Access provides open access to the publications of the Max Planck Research Library for the History and Development of Knowledge. The aim is to disseminate the results of scholarly work – in accordance with the open-access paradigm – to a broad audience rapidly and at low cost. The volumes presented here are directed at scholars and students in a wide range of disciplines. The works are available online both as print-on-demand books and open-access publications and can be accessed, together with additional information.

The EZB is a huge directory of electronic journals which mirrors the central Max Planck Society subscriptions as well as the local licensing situation of the institutes. Access rights to the contents of the individual journals are indicated with "traffic lights". Entries are searchable on journal level.

This bibliographic database is the central access to the specialist information on education. In the center of the service are the specialist literature databases as well as comprehensive collections of information at the various aspects of educational science. -- Diese bibliografische Databank ist der zentrale Einstieg in die pädagogische Fachinformation. Im Mittelpunkt des Services stehen die fachlichen Literaturdatenbanken sowie umfassende Informationssammlungen zu den verschiedenen Aspekten der Erziehungswissenschaft.

Frontiers is a community-oriented open-access academic publisher and research network. It was launched in 2007 by scientists from the Swiss Federal Institute of Technology in Lausanne and aims to provide better tools and services to researchers in the Internet age. Since then, Frontiers has become one of the fastest-growing open-access scholarly publishers: over 400,000 high-quality, peer-reviewed articles have been published in about 200 community-driven journals across more than 300 specialty niches in science, medicine and technology. The Max Planck Society covers article-processing charges for Max Planck authors centrally. Further details are available on the MPDL website.

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.

This database of the European Union (EU) contains the complete EU related terminology in all 24 official languages of the EU. -- Diese Datenbank der Europäischen Union (EU) enthält die gesamte EU-bezogene Terminologie in allen 24 EU-Amtssprachen.

JournalTOCS is the largest, free collection of scholary journal Tables of Contents (TOCs): 29,639 journals including 12,153 selected Open Access journals and 11,312 Hybrid journals from 2930 publishers.

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.

The Max Planck Journal Index provides holdings of a great range of printed journals available within the Max Planck Society. Besides, it contains metadata of electronic journals as loaded from the EZB. The database is updated regularly from the ZDB (twice a year) and the EZB (monthly).

A collaborative effort of the Networked Digital Library of Theses and Dissertations (NDLTD), OCLC, VTLS, and Scirus, the NDLTD Union Catalog contains more than one million records of electronic theses and dissertations. For students and researchers, the Union Catalog makes individual collections of NDLTD member institutions and consortia appear as one seamless digital library of electronic theses and dissertations.

The goal of OAIster is to create a collection of previously difficult-to-access, academically-oriented digital resources that is easily searchable by anyone.

Open Syllabus is a non-profit research organization that collects and analyzes millions of syllabi to support novel teaching and learning applications. Open Syllabus helps instructors develop classes, libraries manage collections, and presses develop books. It supports students and lifelong learners in their exploration of topics and fields. It creates incentives for faculty to improve teaching materials and to use open licenses. It supports work on aligning higher education with job market needs and on making student mobility easier. It also challenges faculty and universities to work together to steward this important data resource. Open Syllabus currently has a corpus of nine million English-language syllabi from 140 countries. It uses machine learning and other techniques to extract citations, dates, fields, and other metadata from these documents. The resulting data is made freely available via the Syllabus Explorer and for academic research. The project was founded at The American Assembly, a public policy institute associated with Columbia University. It has been independent since 2019. All of the syllabi in the current collection are English language documents – including from universities where English is not the primary teaching language.

The OSF Preprints search combines records from various preprint repositories, including arXiv, bioRxiv, Cogprints, PeerJ, PsyArXiv, RePEc and SocArXiv.

Project Gutenberg is a volunteer effort to digitize and archive cultural works. Founded in 1971 by Michael Hart, it is the oldest digital library. Project Gutenberg's mission is "To encourage the creation and distribution of eBooks".