Mathematics

BASE is one of the world's most extensive search engines of networked academic resources. BASE provides more than 150 million documents from more than 7,000 sources, including Illinois Tech's Institutional Repository. You can access the full texts of about 60% of the indexed documents for free (Open Access). BASE is operated by Bielefeld University Library.

The Open Access Directory (OAD) maintains a list of open data repositories as part o their website. While not searchable, the list is broken out by subject area.

Data.gov is a searchable database of public datasets maintained by the U.S. General Services Administration. In addition to the searchable web interface, there are also a number of free APIs.

The Digital Library of Mathematical Functions (DLMF) is an online project at the National Institute of Standards and Technology (NIST) to develop a major resource of mathematical reference data for special functions and their applications. It is intended as an update of Abramowitz's and Stegun's Handbook of Mathematical Functions.

Portal to a number of excellent resources in mathematics including free literature databases such as Zentralblatt MATH and the Electronic Library of Mathematics.

Google Dataset Search is a search engine for datasets. Using a simple keyword search, users can discover freely available datasets hosted in thousands of open access repositories across the Web.

The MERLOT system provides access to curated online learning and support materials and content creation tools, led by an international community of educators, learners and researchers.

Numdan is a searchable database of full-text mathematical research documents: journal articles, seminar and conference proceedings, books and monographs, doctoral theses. While a large part of the content has been digitized starting first known issue from paper volumes, Numdan also acquires newer content that is made freely downloadable after a variable embargo period.

OpenDOAR is the quality-assured, global Directory of Open Access Repositories. We host repositories that provide free, open access to academic outputs and resources. Each repository record within OpenDOAR has been carefully reviewed and processed by a member of our editorial team which enables us to offer a trusted service for the community.

Free public access to over 200,000 full-text documents and bibliographic citations of Department of Energy (DOE) research report literature.

Project Euclid is a partnership of independent publishers of journals, monographs, and conference proceedings in theoretical and applied mathematics and statistics. Some of the publications are open access, while a majority of the sources are partially open, and a few are for subscribers only.

Re3data is a global registry of research data repositories that covers research data repositories from different academic disciplines. In addition to the fully functional search and browse features on the website, they offer a free API to facilitate retrieval of data.

Science.gov is a gateway to over 50 million pages of authoritative selected science information provided by U.S. government agencies, including research and development results.

Unpaywall is a free, open database indexing millions of legally free versions of otherwise paywalled scholarly articles. It also has a downloadable browser extension that integrates into the Chrome and Firefox browsers, allowing users to access millions of legally free research papers as they browse.