Sharetribe - Build your online marketplace business. You don't need a developer.
MarketplaceKit - MarketplaceKit is a platform for building different types of online marketplaces.
Arcadier - Build an online marketplace in minutes, no coding required.
Retaxis - Look no further if you are planning to start an online store or a multivendor marketplace which allows you to sell worldwide.
IZBERG - IZBERG provides mid-size and global B2C and B2B companies with solutions to create scalable and flexible online marketplace.
JaJuMa-Market - All-In-One Multi-Vendor / Online Marketplace Solution. Various Business Models supported.