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