Scribd has launched its own audiobook service, which features 30,000 titles at no extra cost to subscribers of its digital book service.

The launch comes a number of months after Amazon launched an all-you-can-read book service that imitates what Scribd offers.

"Audiobooks are just a good fit for your iPhone or your Android phone, while you're driving or if you're going to sleep," said Scribd CEO Trip Adeler. "They're a very good use case [for reading] and we think it's a big, growing market."

Scribd says that there are no limitations to how many titles subscribers can download, but a few audiobooks could quickly fill most mobile devices. It would be easy to think that most of the titles offered are by unknown authors, but authors offered include the likes of Cormac McCarthy and Haruki Murakami. "The Hunger Games" books are there and there is an even a recorded version of the Bible.

Amazon began offering audiobooks to subscribers a while ago, but there were a limited number of titles available. In fact, it seemed like Amazon's audiobook service was somewhat of an afterthought, being bundled with the 700,000 e-books that are offered with Kindle Unlimited.

Some suggest that the move by Scribd represents a shift in the way that content is consumed online. While Spotify offers unlimited music streaming to its subscribers and companies like Amazon and Netflix do the same for video streaming, there haven't been as many options for e-book fans. Many people are moving away from buying content, with Amazon CFO Tom Szkuta recently saying more customers now prefer to rent content rather than buy it.

Even Apple is likely to move toward a subscription model in the near future, having acquired Beats Music, which is currently a competitor to Spotify.

So what's the catch to the new unlimited access to audiobooks that Scribd has to offer? Well, there really isn't one. Digital rights management (DRM) does not limit the audiobooks, there are some great titles offered by the service, and users can listen to as many audiobooks as they want.

"Audio is a growing category and one that needs additional distribution channels," said Chantel Restivo-Alessi, chief digital officer of HarperCollins Publishers. "By making our audiobooks available through Scribd, we're opening up a much wider market for our authors' works."

Scribd hopes that the addition of audiobooks to its service will help make its offering more robust and appealing to prospective users.