Attributor is an online service that helps news websites and book publishers track illegal or pirated copies of their content on other sites. The service recently released a report on eBook piracy saying that the sales impact of book piracy is highest in the Business and Investing, Professional and Technical and Science categories.

Attributor has also compiled a list of top 25 file hosting website from where anyone can download ebooks without having to pay any share to the book publisher. The list also includes popular sites like, DocStoc and WattPad.

Here’s a complete list of websites that offer pirated ebooks and their respective share in the piracy pie. The book piracy share is calculated based on more than 53,000 book takedown notices sent between July and December 2009.

Website Hosting Pirated eBooks Share of book piracy 35.6% 32.7% 7.4% 3.7% 2.4% 2.1% 2.1% 2.0% 1.5% 1.2% 1.1% 1.1% 1.0% 0.8% 0.6% 0.6% 0.6% 0.6% 0.5% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4%

This study does not attempt to address the issue of determining to what degree pirated books represent financial loss to the industry as it does not estimate how many free downloads might have otherwise resulted in a sale. In other words, this study does not attempt to answer the question, “How many of these pirated books would have been purchased legally if piracy was not an option?”