Cocorico - Cocorico is a state-of-the art Open Source solution to create an Airbnb or Blablacar for anything.
Sharetribe - Build your online marketplace business. You don't need a developer.
Arcadier - Build an online marketplace in minutes, no coding required.
JaJuMa-Market - All-In-One Multi-Vendor / Online Marketplace Solution. Various Business Models supported.
Shopify - Shopify is a powerful ecommerce platform that includes everything you need to create an online store and sell online. Try it free for 14 days.
Retaxis - Look no further if you are planning to start an online store or a multivendor marketplace which allows you to sell worldwide.