OpenCart - A free shopping cart system. OpenCart is an open source PHP-based online e-commerce solution.s
Price2Spy - Price2Spy is a price monitoring, pricing analytics, and repricing tool, meant to help eCommerce professionals keep an eye on their competitors or retailers.
WooCommerce - A freely available eCommerce plugin that enables shop facilities on your WordPress website. Functionality enabling extensions & beautiful themes available.
Skuuudle - Discover, match and monitor your eCommerce competitors.
PrestaShop - Create your online store with PrestaShop's free shopping cart software. Build an ecommerce website for free and start selling online with hundreds of powerful features.
Prisync - Prisync is a competitor price tracking and monitoring software for all sizes of e-commerce companies worldwide.