UK-based SVOD provider Hopster has launched an exclusive partnership with HarperCollins Children’s Books that will bring titles like Judith Kerr’s The Tiger Who Came to Tea and Oliver Jeffers’ Up and Down to the multiplatform service.

Released today in honor of World Book Day, a dozen titles are featured in the app’s newly launched Book Boat section, and are available to Hopster’s UK subscribers.

Additional books will launch on a monthly basis. (Twelve eBooks, two audio books and one video book will be available at all times.)

Hopster debuted in 2013 and has since attracted several partners including investor Sony Pictures Television and Fingerprint, which led to a partnership with the Samsung Kids App.

Hopster also just recently launched on Roku in the US, Canada, France, the UK and Ireland. It is now being used by more than one million families worldwide.