This article analyses the challenges that online marketplaces and e-commerce pose to traditional product liability doctrines. It uses a comparative perspective to examine whether an online platform can be liable to a consumer for a defective product purchased on its platform, and the adaption of product liability law to this challenge in a series of jurisdictions. It reflects on the role of litigation and regulation, focusing on Europe and the United States, and considers reform in a number of jurisdictions in this area. It concludes with proposals for increasing the accountability of online marketplaces for products sold on their websites.