osCommerce is a free, open source online shop software. The default installation includes a large number of features that you can easily enable and configure. You can easily install osCommerce on your website with the help of the Fantastico auto-installer.

With osCommerce shopping cart you can add multiple products on your site, organize them in categories, set discounts and special promotions. osCommerce allows you to set your prices in different currencies and accept all popular payment methods: PayPal, credit cards, cheques. osCommerce has a built-in shipping and tax functionalities.

CREloaded project is built on the source code of osCommerce but it has extra contributions installed. It offers powerful shopping cart solutions in Standard, Pro and Pro B2B editions. With CREloaded you have the ability to distribute coupon codes, the template system is better, and you have an affiliate manager.

Zen cart is being developed by a group of like-minded shop owners, programmers, designers, and consultants who have first-hand experience in e-commerce. Zen Cart is the outcome of their continuous mutual work. It is a free and user-friendly shopping cart, and is distributed as an open source software.

CS-Cart is paid shopping cart software written in PHP & MySQL (The license is a one-time fee of $265 and includes 1 month of free technical assistance at CS-Cart). The CS Shopping Cart is easy to install, has an intuitive template management system (compared to osCommerce) and user-friendly admin area. By default, CS-Cart is integrated with more than 35 popular payment systems such as PayPal, 2CheckOut, GoogleCheckOut, WorldPay, etc. It includes 5 professional templates and their 20 color schemes in all. CS-Cart is a fully multilingual software with multicurrency feature. It has also an advanced Order management tool, Affilate add-on, Product configurator, Feature comparison and Gift Registry modules.

CubeCart is an eCommerce script written in PHP & MySQL. With CubeCart you can setup a powerful online store as long as you have hosting supporting PHP and one MySQL database. CubeCart is very powerful and easy to connect to various payment gateways.

Virtuemart (formerly known as php-Shop) is an independent open-source shopping cart solution. However, it is better known as an e-commerce component for Mambo or Joomla! CMS.

* The installation of VirtueMart on a Mambo site is currently the same as the installation on a Joomla website.

Magento is the latest open source eCommerce platform on the web. It offers professional features, flexibility and control over the look, content, and functionality of the online shop. With Magento you can establish an e-business with convenient product and catalog browser options, extended customer management, advanced analytics, reporting and marketing promotions tools, and much more. Magento has an intuitive administration interface, it is completely scalable and backed by an extensive support network.