Z-Library

Z-Library (z-lib, formerly BookFinder) is a shadow library and file-sharing project for scholarly journal articles, academic and general-interest books. Z-Library says the project provides access to more than 6,754,720 books and 80,759,561 articles as of April 1, 2021. Z-Library also claims to be "The world's largest ebook library" on the project's page for eBooks as well as "The world's largest scientific articles store" in the project's equivalent page for academic articles (booksc.org).
History.
The footer in the project's pages contains the phrase "Free ebooks since 2009." Z-Library is one of the more well known Shadow Libraries, along with Sci-Hub and Library Genesis, with publishers and government organizations usually putting the three in the same category when pursuing anti-piracy cases. UK organization The Publishers Association has attempted to enact ISP level blocks on Z-Library. In late 2015, Publisher Elsevier filed a successful court request that ordered the registrar of bookfi.org to seize the site's domain. Bookfi.org, booksc.org and b-ok.org were included in the 2017 US government report for Notorious Markets.
Functionality.
Contrary to Library Genesis and Sci-Hub, not much is known about Z-Library in terms of its operation, management, commercial status and mission statement. Notably, Z-Library doesn't open its full database to the public. However, Z-Library still retains some community contribution features such as accepting donations and eBook/article submissions from users. B-ok.cc and bookfi.net are also listed as mirrors on Library Genesis's website. In contrast to other shadow library projects, Z-Library encourages its users to create an account, applying rate-limiting to those that don't. There also exists a version of the project on the TOR network, appearing to also include eBooks that have been taken down from the clearnet sites.
Librarians and the Z-Library.
Librarians have been largely professionally silent about the Z-Library. One exception, by Mikael Böök, Library activist, is the essay, "Herding the Wind: A journey to the strange world of the e-library in the autumn of the year 2020." Böök connects the purpose of Z-Library to the Five laws of library science by S. R. Ranganathan. He also notes Michael S. Hart, inventor of the e-book and founder of Project Gutenberg as a precursor of the Z-Library. Böök addresses issues of copyright, the perplexing case of books by Wu Ming, and the role of the World Trade Organization (WTO) and World Intellectual Property Organization (WIPO).