
The Unbelievable Scale of AI’s Pirated-Books Problem
Meta pirated millions of books to train its AI. Search through them here.
The Unbelievable Scale of AI’s Pirated-Books Problem
Meta pirated millions of books to train its AI. Search through them here.
Alex Reisner – March 20, 2025
Meta pirated millions of books to train its AI. Search through them here.

Illustration by Matteo Giuseppe Pani / The AtlanticProduced by ElevenLabs andNews Over Audio (Noa)using AI narration. Listen to more stories on the Noa app.

Updated at 5:40 p.m. ET on March 21, 2025
Editor’s note: This analysis is part of The Atlantic ’sinvestigation into the Library Genesis data set. You can access the search tool directlyhere. Find The Atlantic ’s search tool for movie and television writing used to train AIhere.
When employees at Metastarted developing their flagship AI model, Llama 3, they faced a simple ethical question. The program would need to be trained on a huge amount of high-quality writing to be competitive with products such as ChatGPT, and acquiring all of that text legally could take time. Should they just pirate it instead?
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Meta employees spoke with multiple companies about licensing books and research papers, but they weren’t thrilled with their options. This “seems unreasonably expensive,” wrote one research scientist on an internal company chat, in reference to one potential deal, according to court records. A Llama-team senior manager added that this would also be an “incredibly slow” process: “They take like 4+ weeks to deliver data.” In a message found in another legal filing , a director of engineering noted another downside to this approach: “The problem is that people don’t realize that if we license one single book, we won’t be able to lean into fair use strategy,” a reference to a possible legal defense for using copyrighted books to train AI.
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Court documents released last night show that the senior manager felt it was “really important for [Meta] to get books ASAP,” as “books are actually more important than web data.” Meta employees turned their attention to Library Genesis, or LibGen, one of the largest of the pirated libraries that circulate online. It currently contains more than 7.5 million books and 81 million research papers. Eventually, the team at Meta got permission from “MZ”—an apparent reference to Meta CEO Mark Zuckerberg—to download and use the data set.
This act, along with other information outlined and quoted here, recently became a matter of public record when some of Meta’s internal communications were unsealed as part of a copyright-infringement lawsuit brought against the company by Sarah Silverman, Junot Díaz, and other authors of books in LibGen. Also revealed recently, in another lawsuit brought by a similar group of authors, is that OpenAI has used LibGen in the past. (A spokesperson for Meta declined to comment, citing the ongoing litigation against the company. In a response sent after this story was published, a spokesperson for OpenAI said, “The models powering ChatGPT and our API today were not developed using these datasets. These datasets, created by former employees who are no longer with OpenAI, were last used in 2021.”)
Until now, most people have had no window into the contents of this library, even though they have likely been exposed to generative-AI products that use it; according to Zuckerberg , the “Meta AI” assistant has been used by hundreds of millions of people (it’s embedded in Meta products such as Facebook, WhatsApp, and Instagram). To show the kind of work that has been used by Meta and OpenAI, I accessed a snapshot of LibGen’s metadata—revealing the contents of the library without downloading or distributing the books or research papers themselves—and used it to create an interactive database that you can search here:
There are some important caveats to keep in mind. Knowing exactly which parts of LibGen that Meta and OpenAI used to train their models, and which parts they might have decided to exclude, is impossible. Also, the database is constantly growing. My snapshot of LibGen was taken in January 2025, more than a year after it was accessed by Meta, according to the lawsuit, so some titles here wouldn’t have been available to download at that point.
LibGen’s metadata are quite disorganized. There are errors throughout. Although I have cleaned up the data in various ways, LibGen is too large and error-strewn to easily fix everything. Nevertheless, the database offers a sense of the sheer scale of pirated material available to models trained on LibGen. Cujo , The Gulag Archipelago , multiple works by Joan Didion translated into several languages, an academic paper named “Surviving a Cyberapocalypse”—it’s all in here, along with millions of other works that AI companies could feed into their models.