App Annie, a three-year-old venture that offers sophisticated visualizations of market data and analytics on mobile app sales, is expanding into the e-book market with the launch of App Annie For E-books, a service that will allow e-book publishers and self-publishers to track and analyze e-bookstore sales at the Amazon Kindle Store and Apple’s iBooks store. App Annie For E-books is limited to the Amazon and Apple retail platforms with plans to expand to other retailers in the future.

Used by more than 90% of the publishers who release apps on the iOS platform, App Annie tracks sales and offers analytics on more than 300,000 apps, according to Marcos Sanchez, v-p of worldwide communications at App Annie, during a phone call from Germany where he is attending the Frankfurt Book Fair. “Retail platforms like iTunes and Google Play only give publishers a certain amount of information,” Sanchez said, “we offer more info, automated and we offer a longtail of data from multiple app stores and the ability to slice and dice the data in all kinds of ways.”

App Annie has received more than $15 million in funding from such investors as Sequoia Capital, IDG Capital Partners and Greycroft and the company has about 110 employees in six offices around the world. Sanchez said they expect to have about 150 employess by the end of the year.

The service claims to make tracking and analyzing data “intuitive” and “accessible.” Sanchez said the service was looking to expand into the e-book market, where he said publishers need the same kind of services apps publishers need. “Apps and e-books are bits and bytes, it all digital content and e-book publishers and app publishers have the same problems tracking their sales,” Sanchez explained. “We’ve spent a lot of time figuring out how people want to use data and if publishers want to understand a market and see if they are making money, we can make it easy and quick to do.”

App Annie offers three products for analyzing apps but will launch with two of those services for e-books. Both of the services are free to publishers, who simply open a free App Annie account and plug in their Amazon or iBooks store account information and App Annie For E-books will provide a vivid and detailed visualization of their sales. One product is Analytics, which allows publishers to track all their sales and download data from multiple e-books stores in one simple dashboard. The other product is Store Stats, which stores and offers for display a longtail of data on the rankings of all e-books across geographic markets, genres and calendar dates.

Both services are free for apps and e-books. App Annie generates is revenue by a third product, Intelligence, a premium for-pay service that uses App Annie’s sophisticated algorithms and software tools to give publishers even greater depth, granularity and detail by offering well researched estimates about the app marketplace. Publishers can only look at data for their own titles. App Annie For E-books will not offer the Intelligence mode just yet, Sanchez said, as the service begins to collect data.

Sanchez said App Annie has been talking with trade book publishers about the new service and has a variety of beta testers for the service including self-publishers and small and mid-size publishers. App Annie will be exhibiting at the Frankfurt Book Fair in Hall 6.1 booth D144. “We’re trying to make sure the product makes sense,” Sanchez said.