OpenCart - A free shopping cart system. OpenCart is an open source PHP-based online e-commerce solution.s
Freshservice - Freshservice: the one-stop cloud solution for all your IT management needs.
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.
Freshdesk - Freshdesk is a cloud-based customer support software that lets you support customers through traditional channels like phone and email, social channels like Facebook and Twitter, and your own branded community
WooCommerce - A freely available eCommerce plugin that enables shop facilities on your WordPress website. Functionality enabling extensions & beautiful themes available.
Zendesk - Zendesk is a beautiful, lightweight help-desk solution.