What Is a Shadow Library?

In 2024, the Internet Archive, a massively popular digital library nonprofit, removed more than 500,000 books from its Open Library catalog after losing its appeal for being sued by four U.S. publishers. The publishers argued that the Internet Archive’s lending policy used during the pandemic, in which it loaned multiple e-book copies of a single book at once, infringed on copyright law.

This decision has sparked discussions on the importance and ethics of access to information, bringing free library sites — like shadow libraries — into the spotlight.

What Are Shadow Libraries?

Shadow libraries, or pirate libraries, are online databases of free, readily available content that is otherwise not widely accessible to the public. This content is often text materials like books, textbooks and academic articles, but it can also include software, film and videos or audio files. Materials found on shadow libraries may be normally inaccessible due to paywalls, copyright conditions or region-specific content regulations.

Shadow libraries have their name because they can be considered to operate “in the shadows,” or outside the legal boundaries of copyright and publication guidelines. These libraries may obtain and distribute their content using methods that can violate copyright law, including mass photocopying, web scraping or downloading without author or publisher permission. This aspect has made many shadow libraries fall into a legal gray area — or be considered outright illegal, depending on the country they operate from, the content they share and how they share it.

To evade legal shutdown orders, shadow libraries frequently operate under multiple domain name variations or website mirrors so their databases never fully vanish. They can also operate on the dark web and remain accessible through torrents and the Tor network, ensuring that users can visit their websites even if they are blocked by a country’s internet service providers.

Shadow Libraries and Open Access

Open access refers to publishing where research and academic articles are made free to readers with little to no barriers for access. The practice uses several types of publishing models (such as gold, green and bronze), which determine publishing costs and how content will be allowed to be accessed or shared. 

Shadow libraries are a form of open access publishing, with some of them falling under a black open access model (also known as illegal open access or guerilla open access). Black open access describes publications that do not have an open license or where reuse rights haven’t been granted by copyright owners, meaning its content is being illegally shared online. Shadow libraries like LibGen and Sci-Hub in particular have been dubbed as black open access sites.

Are Shadow Libraries Legal?

Shadow libraries may be considered illegal if they collect and distribute copyrighted works without author permission, as this can violate copyright and intellectual property laws.

“In the United States, with few exceptions, it is illegal to copy and/or distribute copyrighted content without the consent of the copyright owner,” Kristin Grant, intellectual property attorney and managing partner at Grant Attorneys at Law, told Built In. “Shadow libraries appear to be doing just this and it is not clear that their activities would fall within the fair use exception, thereby making these activities unlawful.”

That said, shadow library legality depends on each country’s copyright laws. And with shadow libraries’ ability to host copyrighted works to and from all over the world, this makes legal absolutes even more murky.

Generally, copyright protection is recognized across multiple countries thanks to an international treaty called the Berne Convention for the Protection of Literary and Artistic Works. With this treaty, a work copyrighted in the United States, for example, can receive protections in other member countries. Even so, enforcing a U.S.-copyrighted work in a member country is still more complex than enforcement of the same work in the United States, according to Grant. 

“Though protection is afforded in member countries under the Berne Convention, there may still be certain limitations or requirements that need to be met under the national laws of each country,” she said.

Examples of Shadow Libraries

Shadow libraries exist in various sizes and for different purposes. Here are a few of the largest and most popular shadow libraries:

Library Genesis (LibGen) 

Library Genesis, or LibGen, is a shadow library of scholarly journal articles, academic and general-interest books, comics and magazines. LibGen began as a project by Russian scientists around 2008 to combine collections of Russian-language text material on the Russian-language internet. Today, it is known as one of the largest and oldest shadow libraries on the internet.

Sci-Hub

Sci-Hub is a shadow library for scientific research papers, academic articles and other scientific-related research data. The Sci-Hub project says its goal is to “provide free and unrestricted access to all scientific knowledge ever published in journal or book form.” As of 2017, Sci-Hub was found to contain over 85 percent of articles published in toll access journals.

Z-Library

Z-Library, or Z-Lib, is a shadow library that describes itself as “the world’s largest ebook library.” The database contains general-interest books, textbooks and academic journal articles, with over 80 million articles and 22 million books available. Z-Library reportedly began as a mirror site of Library Genesis, though has since branched off and expanded to include some works that may not be available on LibGen.

Anna’s Archive

Anna’s Archive is a shadow library that mirrors the LibGen and Sci-Hub libraries. It also scrapes content from Z-Library, the DuXiu database and other shadow libraries. Anna’s Archive’s code and data are fully open-source to make the website “resilient to takedowns and ensure the long-term preservation of humanity’s knowledge.” As of 2024, the shadow library estimates itself to have preserved at least 5 percent of the world’s books.

Why Are Shadow Libraries Used? 

Shadow libraries are often a resource for users who may not have the ability — financially or legally — to obtain content through traditional means. This leads to a few reasons for why these types of databases are used:

They’re Free

Shadow libraries regularly provide content completely for free, unlike various bookstores or academic journals. Having free access to information is a value commonly shared by the creators of shadow libraries, and bypassing paywalls stands as one of the major reasons these libraries exist in the first place. In an interview with Textum Dergi, Sci-Hub creator Alexandra Elbakyan said she started the project because “many students and researchers were suffering from paywalls.”

Rory Mir, associate director of community organizing at the Electronic Frontier Foundation, emphasizes the cost-free aspect: “If you are, say, a researcher who doesn’t have access to a piece of expensive research, there is a huge incentive to just get it any way you can,” Mir told Built In. “When people do freely share [research] in a commons, it allows researchers to get that benefit without having the privilege network or economic resources.”

They’re Convenient

Shadow libraries provide immediate access to content that can be paywalled or difficult (and sometimes impossible) to view elsewhere. Content can often be searched by keywords and usually don’t require accounts or personal information for downloads. Plus, the fact shadow libraries exist online means their content can be accessed from virtually anywhere in the world.

“Sometimes it’s about easier access, and that ease might be that a collection is gathered in one place, or that you can access a book, for example, without a trip to the library on campus,” Mirosław Filiciak, associate professor at SWPS University and contributor of Shadow Libraries: Access to Knowledge in Global Higher Education, told Built In.

They’re Often the Only Available Option

Based on physical location, users may not have any legal options for obtaining the content they seek. This could be because of local resources being scarce, or not having access to certain content due to geographical copyright restrictions.

“[Sometimes] shadow libraries are simply the only option to access some material,” Filiciak said. “For example, in Poland, where I work, science is underfunded. Under the state license, universities have access to very small collections, and university budgets generally do not allow them to buy access to a wide range of commercial databases.”

They Preserve Content

Today, lots of media content — like literature, films, television or video games — exist solely in digital format and can’t be obtained physically as a book, disc or cartridge. While convenient for quick distribution, this puts this content at risk of never being accessible again if it is lost, erased or discontinued by publishers. Shadow libraries may house this type of content to ensure it is preserved, and are sometimes the only remaining way to access material at all.

“This is an area for which shadow libraries have great merit,” Filiciak said. For example, a portion of scientific materials existing today were actually “preserved by grassroots, enthusiast-run archives,” he explained. And because of this preservation, this can even revive public interest in materials that are no longer issued or have legally disappeared. “Sometimes,” Filiciak said, “there are paradoxical situations where, in the wave of the retro boom, these old items are brought back onto the market on the basis of unauthorized files from shadow libraries.”

The Ethics of Shadow Libraries

While providing free access to information online, shadow libraries also have the potential to illegally share copyrighted works at scale, causing continuous ethical conversations surrounding their use.

Criticisms of Shadow Libraries

Shadow libraries may obtain their material by any means necessary, which prevents original authors and publishers from earning royalties, as well as poses possible cybersecurity risks for users. Some shadow libraries have been found to scrape metadata databases, been claimed to steal university login credentials to bypass university networks as well as been accused of stealing U.S. military secrets. And because of their massive text collections, shadow libraries have acted as data sources for training large language models, heightening data privacy concerns.

Large publishing corporations have a history of calling for the shutdown of shadow libraries for copyright violation. In 2023, four major U.S. publishers sued LibGen for copyright infringement, determining that its activities “devalue the textbook market and deprive publishers of income from textbook purchases,” according to The Guardian. In 2017, publisher Elsevier similarly sued Sci-Hub and LibGen, and was awarded $15 million in damages due to copyright infringement by the shadow libraries.

Defenses of Shadow Libraries

Not everyone shares these criticisms. Rather, they think academic research should be free and accessible to all. It’s the publishers that are at fault for putting this information behind a paywall in the first place, the logic goes. Plus, researchers are often not paid  — sometimes they have to pay fees themselves — to have their work published in academic journals, so they aren’t financially harmed by having their works shared on shadow libraries.

“We’ve really moved to a world where information can be reproduced and distributed around the world virtually for free, and these are both really vital for the scientific process, global collaboration and knowledge building,” Mir said. “That change should be supercharging science, but we still have publishers that are really holding on to the control of that research.”

Even though it’s illegal in some cases, the use of shadow libraries is a necessary reality for much of academia. In a 2022 study among international researchers, more than half of participants said they have used a scholarly piracy site at least once. This is prevalent in many developing countries, like Indonesia, India and Iran, where universities strive to compete in Western-centric disciplines, but their local libraries and publishing markets can’t meet the demand for new academic texts. As a result, many faculty, students and academic researchers in these countries must rely on shadow libraries to access the material they need.

“I am convinced that among researchers in many parts of the world, especially those outside the wealthy center, shadow libraries are popular because they are a reaction to the realities of professional work,” Filiciak said.

The Future of Shadow Libraries 

Despite legal ramifications and court-mandated shutdowns, shadow libraries will probably never disappear from the internet, at least not completely. Like many online pirate websites, shadow libraries exist under different areas and URLs of the internet — if you shut one down, it’s only a matter of time before more appear. “The cat-and-mouse game [between shadow libraries and publishers] will exist until publishers embrace open access, and then there wouldn’t be a need for [shadow libraries],” Mir said.

In a sense, shadow libraries’ resilience is reflective of their user bases — eager to pursue and preserve information at any stake. 

“So long as there are barriers to people getting important information, they are going to come up with ways to share it,” Mir said. “When we talk about optimistic visions of the future, I really see that as where open access can come and take [knowledge] out of the shadows, and have collaborative information sharing that [helps] not just the researchers, but anyone who benefits from any research.”

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