Shadow libraries are online databases of readily available content that is normally obscured or otherwise not readily accessible. Such content may be inaccessible for a number of reasons, including the use of paywalls, copyright controls, or other barriers to accessibility placed upon the content by its original owners. [1] [2] Shadow libraries usually consist of textual information as in electronic books, but may also include other digital media, including software, music, or films.
Examples of shadow libraries include Anna's Archive, Library Genesis, Sci-Hub and Z-Library, which are popular book and academic shadow libraries [1] [3] and may be the largest public libraries for books and literature.
One of the goals of shadow libraries is to more readily disseminate academic content, especially papers from academic journals. [2] Academic literature has become increasingly expensive, as costs to access information created by scholars have risen dramatically in recent years, especially the cost of books. [4] The term serials crisis has emerged to describe this ongoing trend.
There has also been a concerted international movement, known as the Open Access movement, to make academic knowledge free or very inexpensive. [5] The Open Access movement strives to establish both journals that are free to access (known as open access journals) and free-to-access repositories of academic journal papers published elsewhere. However, many open access journals require academics to pay fees to be published in an open access journal, which disincentives academics from publishing in such journals. [6]
A third reason for the establishment of shadow libraries is the tacit endorsement by many academics of such efforts. [7] Academics are rarely compensated by publishers for their work, regardless of whether their work is published in an open access journal or a conventionally priced journal. Thus, there is now little incentive for academics to disavow shadow libraries. Furthermore, shadow libraries greatly increase the impact of academics whose work is made available. According to one study from Cornell University, articles that are on Sci-Hub receive 1.72 times as many citations as articles from journals of similar quality that are not available on Sci-Hub. [8]
Content hosted by some shadow libraries may be hosted without the consent of the original owners of the material. This may make some shadow libraries illegal; however, as researchers are not required to disclose the means by which they access academic material, it is difficult to monitor the use of illegally accessed academic papers. Not all authors agree with trying to compromise access to shadow libraries. [9]
The legality of directing individuals to shadow libraries is broadly undetermined. There is currently no consensus among legal authorities in the United States and Europe as to what extent advertising shadow libraries constitutes a criminal offense. There are currently no settled cases determining whether it is permissible by academics to directly provide links to shadow libraries, though threats of legal action by academic publishers regarding such references have occurred in isolated incidents. Legal action against researchers remains uncommon. [10]
Although most academics are not penalized for distributing their published works independently and freely (therefore obviating the need for shadow libraries in the first place), there are reports of academic publishers threatening such academics with legal action. [11]
Shadow libraries (or their content databases) make use of BitTorrent (mainly for database dumps), dark web and IPFS technologies to increase their resilience or distribute loads. [12] [13] [14] [15] [16] In the case of Anna's Archive, the software is developed and made accessible as open source software, enabling code development by any volunteer and mirrors or forks, with the site claiming that "if we get taken down we'll just pop right up elsewhere, since all our code and data is fully open source". [17] [18]
The Internet Archive is an American nonprofit digital library founded on May 10, 1996, and chaired by free information advocate Brewster Kahle. It provides free access to collections of digitized materials including websites, software applications, music, audiovisual and print materials. The Archive also advocates for a free and open Internet. As of February 4, 2024, the Internet Archive holds more than 44 million print materials, 10.6 million videos, 1 million software programs, 15 million audio files, 4.8 million images, 255,000 concerts, and over 835 billion web pages in its Wayback Machine. Its mission is committing to provide "universal access to all knowledge".
JSTOR is a digital library of academic journals, books, and primary sources founded in 1994. Originally containing digitized back issues of academic journals, it now encompasses books and other primary sources as well as current issues of journals in the humanities and social sciences. It provides full-text searches of almost 2,000 journals. Most access is by subscription but some of the site is public domain, and open access content is available free of charge.
The Invisible Internet Project (I2P) is an anonymous network layer that allows for censorship-resistant, peer-to-peer communication. Anonymous connections are achieved by encrypting the user's traffic, and sending it through a volunteer-run network of roughly 55,000 computers distributed around the world. Given the high number of possible paths the traffic can transit, a third party watching a full connection is unlikely. The software that implements this layer is called an "I2P router", and a computer running I2P is called an "I2P node". I2P is free and open sourced, and is published under multiple licenses.
An archivist is an information professional who assesses, collects, organizes, preserves, maintains control over, and provides access to records and archives determined to have long-term value. The records maintained by an archivist can consist of a variety of forms, including letters, diaries, logs, other personal documents, government documents, sound and/or picture recordings, digital files, or other physical objects.
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.
An internet leak is the unauthorized release of information over the internet. Various types of information and data can be, and have been, "leaked" to the Internet, the most common being personal information, computer software and source code, and artistic works such as books or albums. For example, a musical album is leaked if it has been made available to the public on the Internet before its official release date.
qBittorrent is a cross-platform free and open-source BitTorrent client written in native C++. It relies on Boost, OpenSSL, zlib, Qt 6 toolkit and the libtorrent-rasterbar library, with an optional search engine written in Python.
Tribler is an open source decentralized BitTorrent client which allows anonymous peer-to-peer by default. Tribler is based on the BitTorrent protocol and uses an overlay network for content searching. Due to this overlay network, Tribler does not require an external website or indexing service to discover content. The user interface of Tribler is very basic and focused on ease of use instead of diversity of features. Tribler is available for Linux, Windows, and OS X.
File sharing is the practice of distributing or providing access to digital media, such as computer programs, multimedia, documents or electronic books. Common methods of storage, transmission and dispersion include removable media, centralized servers on computer networks, Internet-based hyperlinked documents, and the use of distributed peer-to-peer networking.
An open-access monograph is a scholarly publication usually made openly available online with an open license. These books are freely accessible to the public, typically via the internet. They are part of the open access movement.
Mirror sites or mirrors are replicas of other websites. The concept of mirroring applies to network services accessible through any protocol, such as HTTP or FTP. Such sites have different URLs than the original site, but host identical or near-identical content. Mirror sites are often located in a different geographic region than the original, or upstream site. The purpose of mirrors is to reduce network traffic, improve access speed, ensure availability of the original site for technical or political reasons, or provide a real-time backup of the original site. Mirror sites are particularly important in developing countries, where internet access may be slower or less reliable.
The InterPlanetary File System (IPFS) is a protocol, hypermedia and file sharing peer-to-peer network for storing and sharing data in a distributed file system. IPFS uses content-addressing to uniquely identify each file in a global namespace connecting IPFS hosts.
Library Genesis (LibGen) is a file-sharing based shadow library website for 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 comprises 88,343,822 files.
#ICanHazPDF is a hashtag used on Twitter to request access to academic journal articles which are behind paywalls. It began in 2011 by scientist Andrea Kuszewski. The name is derived from the meme I Can Has Cheezburger?
Alexandra Asanovna Elbakyan is a Kazakhstani computer programmer and creator of the website Sci-Hub, which provides free access to research papers without regard for copyright. According to a study published in 2018, Sci-Hub provides access to nearly all scholarly literature.
The Guerilla Open Access Manifesto is a document written by Aaron Swartz in 2008 that supports the Open Access movement. The goal of the Open Access movement is to remove barriers and paywalls that may prohibit the general public from accessing scientific research publications. Swartz was an activist who fought against the restrictions that were placed on scholarly articles and for the right of all people to have access to scientific research.
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.
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".