Spotify users in the U.S. are now able to buy and listen to over 300,000 different audiobook titles, the company announced Tuesday.

The streaming company’s move into audiobooks marks its latest attempt to make the platform a one-stop-shop for all things audio. Spotify introduced podcasts in 2015 and is now home to more than 4.4 million of them, according to its second-quarter earnings report.

The firm decided to introduce audiobooks because they represent a “substantial untapped market,” Nir Zicherman, Spotify’s vice president and global head of audiobooks and gated content, said in Tuesday’s release. Zicherman said the segment is growing by about 20% year over year despite making up just a 6% to 7% share of the current book market.

Following the move, Spotify will enter a fierce competition with Amazon’s Audible, which was dominating the market in 2018 with 41% market share, according to Codex Group, and Amazon also sells e-books under its own brand. Other competitors include Apple, Google, and Rakuten, which has partnered with Walmart.

US-based Spotify users who want to listen to audiobooks can find them in their search, library and their curated recommendations on their homepage. The audiobooks will feature a lock icon over the play button to indicate that they need to be purchased.

Once a book is purchased, users will be able to bookmark their place in the audiobook, control their listening speed and download the content for offline listening.

Spotify plans to introduce audiobooks to new markets and add new features after the initial U.S. launch.