We all know that Amazon is the largest retailer of ebooks in the world, but which online book subscription service has managed to attract the most customers? Amazon was the pioneer of ebook retail business, but it wasn’t the first company that provided customers with all-you-can-eat book service for a low monthly fee. Nonetheless, Amazon has already managed to take a major market share of the emerging book subscription service business.

Nielsen Books & Consumers Market Research has published a report that includes a ranking for ebook subscription services. The services with the biggest number of customers are:

1. Kindle Unlimited
2. Safari Books Online
3. Scribd
4. Oyster
5. Skillsoft
6. 24 Symbols
7. Entitle
8. Blloon

Nielsen has ranked Amazon Prime as an ebook subscription service, but Prime is not comparable with other ranked services. Prime is primarily a product delivery service that also includes access to a number of digital products.