The cost of authorship slots on studies produced by paper mills ranges from less than US$100 to more than $5,000, an analysis found. Credit: Ievgen Chabanov/Alamy

Researchers have amassed a data set of thousands of advertisements selling research-paper authorships online, shedding light on the global marketplace for academic fraud.

The collection — the largest of its kind — contains more than 18,700 adverts that were posted between March 2020 and early April 2026 by seven paper mills — businesses that produce fake or low-quality research and sell authorships . Together, the companies cater to academics in the Middle East, Central Asia, Eastern Europe and India.

Authorship for sale: Nature investigates how paper mills work

An analysis of the advert data found that a first-author slot on an article sold by a paper mill costs a median value of nearly US$800, with prices ranging from $57 to more than $5,600.…