Sharetribe - Build your online marketplace business. You don't need a developer.
OpenCart - A free shopping cart system. OpenCart is an open source PHP-based online e-commerce solution.s
Arcadier - Build an online marketplace in minutes, no coding required.
WooCommerce - A freely available eCommerce plugin that enables shop facilities on your WordPress website. Functionality enabling extensions & beautiful themes available.
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.
IZBERG - IZBERG provides mid-size and global B2C and B2B companies with solutions to create scalable and flexible online marketplace.