An open-access search engine that indexes scholarly articles across disciplines and formats. Widely used to increase article visibility and citations.

A DOI registration agency that ensures persistent linking and reliable metadata for scholarly publications.

BASE (Bielefeld Academic Search Engine) is an academic search engine that provides access to scholarly resources from repositories, digital collections, and open-access sources.

Leiden University’s unified library discovery system that indexes books, journals, digital materials, and other resources across its collections.

Harvard Library’s unified catalog (HOLLIS), providing a single search of books, articles, media, and other resources.

Bucknell University’s subject-based research catalog that indexes journals, articles, and resources by academic discipline.

An international directory managed by the ISSN International Centre that indexes open access scholarly resources, including journals, conference proceedings, and repositories.

An AI-powered academic search engine that indexes over 200 million scholarly papers, extracting meaning and connections to help researchers discover and understand relevant literature.

The world’s largest library catalog, providing access to bibliographic records from thousands of libraries worldwide. It enhances the discoverability and accessibility of scholarly publications through global library networks.