Scribd, the document sharing service for the Internet, announced a new subscription service for digital books, in a model similar to Netflix (movies and TV) and Spotify (music). Through a monthly fee, the user can access a collection of “thousands of books” stored on the site without having to buy every copy of the book before reading.

The key selling point of the subscription service is a partnership with HarperCollins, one of the major publishing partner and big five publishers. The partnership allows access a majority of the HarperCollins US and HarperCollins Christian backlist catalog for Scribd’s digital book subscription service. The other publishers include E-Reads, Kensington, Red Wheel/Weiser, Rosetta Books, Sourcebooks, and Workman.

According to Scribd, there are currently over 40 million books available for readers in more than 100 different countries and written in more than 80 different languages. The company began offering subscribers access the site to an increasing amount of e-books, but only now announced the new pay to read service mode. The company will charge $9 per month for unlimited access to its library.

“Since starting Scribd six years ago, we have gained a lot of experience building a library of books and written works, growing a global community, and gathering data on what readers and publishers want,” said Trip Adler, CEO and co-founder of Scribd. “Those insights have helped us build a product that we believe delivers on a new and better reading experience by giving our customers instant access to a vast collection of books to read, across a wide array of the top digital devices, all for one low monthly price. We are thrilled to be working with HarperCollins on such an innovative and pioneering partnership.”

With a login id, subscribers will be able to browse through books using iPhone and iPad, mobile devices running on Google Android OS, and any personal computer with a Web browser.

HarperCollins, which is owned by News Corp., offers unlimited access to most of HarperCollins’ back catalog. However, the recent best sellers from Harper Collins aren’t included in the subscription service, although customers will be able to buy new titles individually on Scribd’s site.

“With 80 million active users, the Scribd platform is reaching a vast global audience of readers. HarperCollins is excited to reach an innovative partnership with Scribd that monetizes its audience through traditional retail and a subscription offer for our backlist titles,” said Brian Murray, President and CEO, HarperCollins Publishers Worldwide. “HarperCollins authors will benefit from extended reach, increased discovery, and improved royalty streams.”

A book industry’s version of Netflix

In the market for digital books, the Scribd will face major competition from companies such as Apple and Amazon, which currently sell e-books through their online stores. Like Amazon, which offers apps for the Kindle and other platforms, Scribd will be present in most models of mobile devices.

The 29-year-old entrepreneur Trip Adler service evolved gradually over the past year as he tracked the success of Spotify and Netflix in the subscription model. The new subscription service makes sense for the young entrepreneur as it already has large number of people that use Scribd and many of those users are already paying a subscription fee.

“Scribd can convert these people over to the book subscriptions,” says Jan Johnson of Red Wheel Weiser Books. “We are all for this, and we think it will just expand our audience. People will either read a book there, on the service, or buy the book in some other way if they want to keep it in their own library — either their electronic library or their real library. Some people still read books on paper.”

For Adler, the e-book subscription service can boost new revenue stream for the company as well as for publishers just like Netflix do for its business. Netflix currently has 37 million subscribers who pay $8 per month to watch movies and TV shows on any device with an Internet connection.

“Netflix is worth about $18 billion. Spotify is worth about $3 billion,” Adler says. “I don’t see why there isn’t a similar opportunity in this space.”

But the real question is how the publishers will satisfy authors with the new model of Scribd. The mode is not a steady stream of income for authors. It almost works best as a marketing vehicle as opposed to a revenue generator. Scribd’s success will likely depend on its ability to differentiate itself from those competitors.