Social media platform Reddit sued the artificial intelligence company Perplexity AI and three other entities on Wednesday, alleging their involvement in an "industrial-scale, unlawful" economy to "scrape" the comments of millions of Reddit users for commercial gain.

Reddit`s lawsuit in a New York federal court takes aim at San Francisco-based Perplexity, maker of an AI chatbot and "answer engine" that competes with Google, ChatGPT and others in online search.

Also named in the lawsuit are Lithuanian data-scraping company Oxylabs UAB, a web domain called AWMProxy that Reddit describes as a "former Russian botnet," and Texas-based startup SerpApi, which lists Perplexity as a customer on its website.

It`s the second such lawsuit from Reddit since it sued another major AI company, Anthropic, in June.

But the lawsuit filed Wednesday is different in the way that it confronts not just an AI company but the lesser-known services the AI industry relies on to acquire online writings needed to train AI chatbots.

"Scrapers bypass technological protections to steal data, then sell it to clients hungry for training material. Reddit is a prime target because it`s one of the largest and most dynamic collections of human conversation ever created," said Ben Lee, Reddit`s chief legal officer, in a statement Wednesday.

Perplexity said it has not yet received the lawsuit but "will always fight vigorously for users` rights to freely and fairly access public knowledge. Our approach remains principled and responsible as we provide factual answers with accurate AI, and we will not tolerate threats against openness and the public interest."

SerpApi`s customer success director, Ryan Schafer, said in an email: "We strongly disagree with Reddit`s allegations and intend to vigorously defend ourselves in court."

Oxylabs didn`t immediately respond to a request for comment Wednesday. AWMProxy could not immediately be reached for comment.

Reddit compares the companies it is suing to "would-be bank robbers" who can`t get into the bank vault, so they break into the armored truck instead. The lawsuit alleges they are evading Reddit`s own anti-scraping measures while also "circumventing Google`s controls and scraping Reddit content directly from Google`s search engine results."

Lee said that because they`re unable to scrape Reddit directly, "they mask their identities, hide their locations, and disguise their web scrapers to steal Reddit content from Google Search. Perplexity is a willing customer of at least one of these scrapers, choosing to buy stolen data rather than enter into a lawful agreement with Reddit itself."

Reddit made a similar argument in its lawsuit against Anthropic, alleging that the company ignored Reddit`s appeals to cease using its content. That case was initially filed in California Superior Court but was later moved to federal court and has a hearing scheduled for January.

Along with digitized books and news articles, websites such as Wikipedia and Reddit are deep troves of written materials that can help teach an AI assistant the patterns of human language.

Reddit has previously entered licensing agreements with Google, OpenAI and other companies that are paying to be able to train their AI systems on the public commentary of Reddit`s more than 100 million daily users.

The licensing deals helped the 20-year-old online platform raise money ahead of its Wall Street debut as a publicly traded company last year.