Woongjin Thinkbig Book Subscription (Chaekdareun)

What's in the box: Membership gives access to age-matched children's book sets and collections, plus a tablet reading app, with club points and a buyback option.

Woongjin Thinkbig is one of South Korea's best known children's education publishers, and its book subscription runs through the Woongjin Booksclub membership. The company calls the club the biggest library in the world. Membership includes a buyback option and club points, and children read on a tablet app. Book sets and full collections cover ages from before birth through elementary school and into middle school. You can filter them by age and by area, such as literature, history, science, art and emotional development. A free reading test claims to measure a child's reading level, tastes and temperament so it can suggest titles. Featured series include O! Playing, a set of interactive sound board books for toddlers, and a Hanja (Chinese character) series built around the popular Shinbi Apartment characters. The site is entirely in Korean and is clearly built for families in Korea, so shoppers outside the country will struggle to use it. The main pages do not list prices or contract terms. Instead, the company relies on consultations and seasonal sign-up gifts, so expect to talk to a salesperson before you learn the real cost. Customer support is by phone on weekdays. For Korean-speaking parents who want a large, organized catalog from an established publisher, it is a solid choice. Families who want a simple monthly box with clear pricing may find it too much.