Most of the HTRC services require an account to log in and interact with the tools, though HathiTrust+Bookworm is available without an account.
Register for an account by going to the HTRC Analytics main page and choosing "Sign up" via the link at the top of the page. Anyone possessing an email address from a nonprofit institution of higher education is allowed to register, including those whose institutions are not HathiTrust members.
The HathiTrust Research Center (HTRC) enables computational access for nonprofit and educational users to published works in the public domain and (on limited terms) to in-copyright works from the HathiTrust collection.
The HTRC is a collaborative research center launched jointly by Indiana University and the University of Illinois, along with the HathiTrust Digital Library, to help meet the technical challenges of dealing with massive amounts of digital text that researchers face by developing cutting-edge software tools and cyberinfrastructure to enable advanced computational access to the growing digital record of human knowledge.
HTRC AnalyticsA set of tools for assembling collections of digitized text and performing text analysis on them.
HathiTrust+BookwormA tool for visualizing and analyzing word usage trends in the 4.8 million public domain works in the HathiTrust Digital Library. Provides access to the texts in which the words appear.