Unlimited music streaming services are still struggling to make a profit, but Amazon is turning to its bread and butter for its next subscription service: Books.

Amazon is testing a new ebook and audiobook service that will give subscribers unlimited access to over 600,000 titles, according to spotting by Kindle Book forum users, but it won’t come with your Amazon Prime subscription.

The new service, called ‘Kindle Unlimited,’ will cost subscribers $9.99 for access to all titles and audiobooks. Test pages for the program were quickly pulled down after they were posted on forums, but you can still dig them out of Google cache to get a look at the upcoming titles.

Kindle Unlimited has been rumored for a few months and will see the retail giant take on existing ebook subscription services like Oyster and Scribd.

One defining quality of Kindle Unlimited could be its titles with Whisper for Voice audiobooks, as well as the company’s close relationship with publishers after peddling their books for two decades – though it should be notes that relations aren’t too great right now.

Oyster and Scribed have managed to secure deals with Simon & Schuster and HarperCollins to make their e-books available, but Amazon still hasn’t signed up any of the major 5 publishers for Kindle Unlimited, but you better believe Bezos and his minions are working hard to get U.S. publishers signed up before launch, whenever that is.

Via: GigaOM