BitTorrent, also referred to as simply torrent, is a communication protocol for peer-to-peer file sharing (P2P), which enables users to distribute data and electronic files over the Internet in a decentralized manner. The protocol is developed and maintained by Rainberry, Inc., and was first released in 2001.
WorldCat is a union catalog that itemizes the collections of tens of thousands of institutions, in many countries, that are current or past members of the OCLC global cooperative. It is operated by OCLC, Inc. Many of the OCLC member libraries collectively maintain WorldCat's database, the world's largest bibliographic database. The database includes other information sources in addition to member library collections. OCLC makes WorldCat itself available free to libraries, but the catalog is the foundation for other subscription OCLC services. WorldCat is used by librarians for cataloging and research and by the general public.
The Pirate Bay is an online index of digital content of entertainment media and software. Founded in 2003 by Swedish think tank Piratbyrån, The Pirate Bay allows visitors to search, download, and contribute magnet links and torrent files, which facilitate peer-to-peer file sharing among users of the BitTorrent protocol.
Crossref is a nonprofit open digital infrastructure organisation for the global scholarly research community. Uniquely and persistently recording and connecting knowledge through open metadata and identifiers for all research objects such as grants and articles. It is the largest digital object identifier (DOI) Registration Agency of the International DOI Foundation. It has 19,000 members from 150 countries representing publishers, libraries, research institutions, and funders and was launched in early 2000 as a cooperative effort among publishers to enable persistent cross-platform citation linking in online academic journals. As of July 2023, Crossref identifies and connects 150 million records of metadata about research objects made openly available for reuse without restriction. They facilitate an average of 1.1 billion DOI resolutions every month, and they see 1 billion queries of the metadata every month.
TorrentFreak (TF) is a blog dedicated to reporting the latest news and trends on the BitTorrent protocol and file sharing, as well as on copyright infringement and digital rights.
BTDigg is the first Mainline DHT search engine. It participated in the BitTorrent DHT network, supporting the network and making correspondence between magnet links and a few torrent attributes which are indexed and inserted into a database. For end users, BTDigg provides a full-text database search via a Web interface. The Web part of its search system retrieved proper information by a user's text query. The Web search supported queries in European and Asian languages. The project name was an acronym of BitTorrent Digger. It went offline in June 2016, reportedly due to index spam.
KickassTorrents was a website that provided a directory for torrent files and magnet links to facilitate peer-to-peer file sharing using the BitTorrent protocol. It was founded in 2008 and by November 2014, KAT became the most visited BitTorrent directory in the world, overtaking The Pirate Bay, according to the site's Alexa ranking. KAT went offline on 20 July 2016 when the domain was seized by the U.S. government. The site's proxy servers were shut down by its staff at the same time.
OurResearch, formerly known as ImpactStory, is a nonprofit organization that creates and distributes tools and services for libraries, institutions and researchers. The organization follows open practices with their data, code, and governance. OurResearch is funded by the Alfred P. Sloan Foundation, the National Science Foundation, and Arcadia Fund.
Nyaa Torrents is a BitTorrent website focused on East Asian media. It is one of the largest public anime-dedicated torrent indexes.
CORE is a service provided by the Knowledge Media Institute based at The Open University, United Kingdom. The goal of the project is to aggregate all open access content distributed across different systems, such as repositories and open access journals, enrich this content using text mining and data mining, and provide free access to it through a set of services. The CORE project also aims to promote open access to scholarly outputs. CORE works closely with digital libraries and institutional repositories.
RARBG was a website that provided torrent files and magnet links to facilitate peer-to-peer file sharing using the BitTorrent protocol. From 2014 to 2023, RARBG repeatedly appeared in TorrentFreak's yearly list of most visited torrent websites. It was ranked 4th as of January 2023. The website did not allow users to upload their own torrents.
Library Genesis (LibGen) is a shadow library project for file-sharing access to scholarly journal articles, academic and general-interest books, images, comics, audiobooks, and magazines. The site enables free access to content that is otherwise paywalled or not digitized elsewhere. LibGen describes itself as a "links aggregator", providing a searchable database of items "collected from publicly available public Internet resources" as well as files uploaded "from users".
Sci-Hub is a shadow library website that provides free access to millions of research papers, regardless of copyright, by bypassing publishers' paywalls in various ways. Unlike Library Genesis, it does not provide access to books. Sci-Hub was founded in Kazakhstan by Alexandra Elbakyan in 2011, in response to the high cost of research papers behind paywalls. The site is extensively used worldwide. In September 2019, the site's operator(s) said that it served approximately 400,000 requests per day. In addition to its intensive use, Sci-Hub stands out among other shadow libraries because of its easy use/reliability and because of the enormous size of its collection; a 2018 study estimated that Sci-Hub provided access to 95% of all scholarly publications with issued DOI numbers, and on 15 July 2022, Sci-Hub reported that its collection comprised 88,343,822 files.
The Torrent Project or Torrent Search Project was a metasearch engine for torrent files, which consolidated links from other popular torrent hosting pages such as ExtraTorrent. It was available as an alternative and successor for the closed Torrentz.eu and KickassTorrents sites, and its index included over 8 million torrent files, and had a clean, simple interface. Beyond allowing torrent files of popular films, it also carried self-produced content. It had an API that allowed the search function to be integrated into applications, and the news-site TorrentFreak suggested that it could have allowed streaming in the future. It had adopted the Torrents Time plugin.
Microsoft Academic was a free internet-based academic search engine for academic publications and literature, developed by Microsoft Research in 2016 as a successor of Microsoft Academic Search. Microsoft Academic was shut down in 2022. Both OpenAlex and The Lens claim to be successors to Microsoft Academic.
The Initiative for Open Citations (I4OC) is a project launched publicly in April 2017, that describes itself as: "a collaboration between scholarly publishers, researchers, and other interested parties to promote the unrestricted availability of scholarly citation data and to make these data available." It is intended to facilitate improved citation analysis.
OpenCitations is a project aiming to publish open bibliographic citation information in RDF. It produces the "OpenCitations Corpus" citation database in the process.
Z-Library is a shadow library project for file-sharing access to scholarly journal articles, academic texts and general-interest books. It began as a mirror of Library Genesis, but has since expanded dramatically.
FitGirl Repacks is a website distributing pirated video games. FitGirl Repacks is known for "repacking" games – compressing them significantly so they can be downloaded and shared more efficiently. TorrentFreak listed FitGirl Repacks at sixth in 2021 and at ninth in 2020's Top 10 Most Popular Torrent Sites lists.
Anna's Archive is a search engine for shadow libraries. It was founded by the Pirate Library Mirror, a team of anonymous archivists, in direct response to law enforcement efforts to close down Z-Library in 2022. It describes itself as a project that aims to "catalog all the books in existence" and to "track humanity's progress toward making all these books easily available in digital form".
