WooCommerce - A freely available eCommerce plugin that enables shop facilities on your WordPress website. Functionality enabling extensions & beautiful themes available.
Snipcart - Snipcart is a fully customizable, HTML and JavaScript-based shopping cart for any website. Get set up in seconds, integrate in minutes.
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.
BigCommerce - BigCommerce provides ecommerce software solutions and shopping cart software for online businesses. Try it free and start selling your products online today!
Apicart - Add a Shopping Cart to your website, mobile or desktop app in minutes. Code less, do more!
EcWid - Ecwid E-commerce Shopping Cart is Fast and Easy to Use! Works with Wordpress, Drupal, Facebook and Much More! Start Selling Fast Online Now with Ecwid.