Amazon is in the middle of testing a new e-book subscription service dubbed Kindle Unlimited, GigaOm reported on Wednesday. The program would offer access to 600,000 titles and cost members $9.99 per month.

The Kindle Boards forum surfaced screenshots of test pages that revealed the program was in the works. Subscribers would get access to audiobooks as well as e-books, though the screenshotted pages didn't specify how many of the latter. Titles shown on the demo page include Moneyball, Water for Elephants, and Twelve Years a Slave.

Kindle Unlimited would be entering competition with services like Oyster, which costs $9.95 per month and gives access to "over 500,000 books," and Scribd, which has over 400,000 books for $8.99 per month. It would also be moving on Audible's territory, which has a catalog of 150,000 audiobooks available for $14.95 per month.

Amazon's program would expand on the Kindle Owners Lending Library, which allows Prime subscribers who own Kindles to borrow one free e-book from a small pool of available titles each month. Amazon took its time deactivating the live pages that showed the program was in the works, and some are still available in Google cache.