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.
Kreezalid - Marketplace building solution for small to midsize firms
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.