WorldCat serves as a centralized database that enables users to locate materials and identify which libraries hold them. It includes a vast array of materials, ranging from books and manuscripts to music recordings and videos. Users can search for specific titles, authors, subjects, or keywords, and WorldCat provides a list of libraries that have the desired item in their collections.

 is one of the world's most voluminous search engines especially for academic web resources. BASE provides more than 300 million documents from more than 10,000 content providers. You can access the full texts of about 60% of the indexed documents for free (Open Access). BASE is operated by Bielefeld University Library.

Unpaywall is a free web browser extension and database that provides access to scholarly research articles that are typically behind paywalls. It is designed to help users find legal open access versions of research papers, making scholarly content more accessible to the general public.

Google Scholar provides access to scholarly material from various publishers, universities, and scholarly societies. It indexes content from academic publishers, institutional repositories, and other websites that provide scholarly information. The search results in Google Scholar often include peer-reviewed papers, theses, dissertations, conference papers, technical reports, and other scholarly publications.

OAister is a union catalog of millions of records that represent open access resources. This catalog was built through harvesting from open access collections worldwide using the Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH). Today, OAIster includes more than 50 million records that represent digital resources from more than 2,000 contributors. is the website of the CORE service, and it serves as a search engine for academic publications. It harvests research articles from various sources, including institutional repositories, subject repositories, and journals, and makes them available for users to search and access.

Scite is an AI-driven platform transforming how we engage with scientific literature. It offers a meticulous overview of a study's citation network, providing context and impact insights. By classifying citations as supporting, mentioning, or disputing, scite unveils the credibility and interpretational nuances of research papers. This novel approach refines academic investigation, promotes transparency, and elevates scientific communication. Scite's user-friendly interface easily integrates into researchers' workflows, enabling data-driven decisions and high-impact research prioritization. By upgrading the discoverability and evaluation of academic literature, scite is a pivotal tool reshaping the scientific community's understanding of research significance and reliability. is an innovative scholarly platform, fostering scientific collaboration and knowledge dissemination. With a vast repository of peer-reviewed articles spanning diverse disciplines, it empowers researchers to share their findings and engage in dynamic discussions. Offering transparent post-publication peer review, it ensures rigorous evaluation of research. ScienceOpen's unique features, such as personalized research collections and citation networks, facilitate efficient information discovery and exploration. Bridging the gap between researchers and the public, it promotes open access to cutting-edge science. Embracing the spirit of open science, accelerates the advancement of knowledge and fosters a vibrant global scientific community. is an integrated research platform designed to support the scholarly community in exploring and understanding research literature. It offers comprehensive access to academic publications, grants, patents, clinical trials, and policy documents, creating a rich and interconnected knowledge database. Researchers can access a vast collection of publications from various disciplines, along with citation and altmetric data, to assess the impact of research. The platform's intuitive interface and powerful analytics tools enable users to uncover valuable insights and trends, fostering collaboration and innovation within the academic world. serves as a valuable resource for academics, institutions, and organizations seeking to stay at the forefront of scientific discovery.

Litmaps is a digital platform offering a visual and interactive way to explore literary works and their connections. Users can navigate through an intricate web of books, authors, and genres, gaining insights into relationships and influences within the literary world. Through dynamic maps and links, Litmaps provides a unique perspective on the evolution of literature and the interconnectedness of literary creations. It serves as a valuable tool for scholars, readers, and enthusiasts alike, fostering a deeper understanding of literary history and fostering discovery of new reading avenues.

Index Copernicus is a scientific indexing service that provides information about scientific journals, conference proceedings, and other publications. It aims to facilitate the dissemination of scientific knowledge and to help researchers, scientists, and institutions assess the quality and impact of scientific literature. is a comprehensive and open platform for scholarly and patent research. It provides access to a vast amount of academic and patent-related information, making it a valuable resource for researchers, inventors, and intellectual property professionals. is a tool that helps users access academic papers quickly and conveniently. It simplifies the process of obtaining research papers and articles by providing direct links to the full text of scholarly articles through a browser extension or web app.

Scilit is a comprehensive content aggregator platform for scholarly publications. It is developed and maintained by the open access publisher MDPI AG . It is offered for free to scientists, scholars and the interested general public. Using widely automated approaches to sourcing and curating data, we cover newly published content from a variety of data sources within hours or days.