Scribd Inc. has taken $22 million Series D in a round led by Khosla Ventures that included Redpoint Ventures, Charles River Ventures and Silicon Valley Bank.

As part of the deal Khosla Ventures partner Keith Rabois will join Scribd’s board as an observer.

“We had a fantastic 2014 at Scribd. We launched audiobooks with 30,000 titles from publishers like Blackstone and Scholastic. We also doubled our e-Book titles, adding content from 1,000+ publishers – including Big 5 publishers Harper Collins and Simon & Schuster – along with industry leaders like Harlequin, Houghton Mifflin, Lonely Planet, Perseus and Wiley,” co-founder and CEO of Scribd Trip Adler said in a statement. “This new funding round will enable us to work towards achieving our goal of creating the most comprehensive library of the future for our millions of users around the world.”

The digital library and e-book subscription service was founded in 2006 with seed funding of $12,000 by YCombinator. Since its launch in 2007 Scribd now boasts of more than 80 million monthly readers accessing a range of books and documents worldwide.

“The subscription model has already transformed the way we consume content like film and music, and Scribd is doing the same with books,” Khosla Ventures Partner Keith Rabois adds.

Perhaps best known for its document hosting and embeds (Scribd is regularly used to embed documents on third party sites)  the company also offers a Spotify like service for ebooks and is available on iOS, Android, Kindle Fire, Nook tablets and the web.

The new money, which brings total funding of Scribd to $47.8 million, will be used to “accelerate hiring, content acquisition efforts and international expansion.”