eCommerce
This is absolutely free under General Public License, is extremely easy to install and run but vastly popular as well. It powers more than 200,000 online stores, which makes it difficult to separate out your store from others. To differentiate yourself, you need to install multiple add-ons available, which however are not free.
Magento
Boasting of a top client list including Samsung, Nespresso and Stussy that use this software for powering online stores, this platform is growing very fast. Though the Community Edition is free, the multiple features loaded Enterprise edition has to be paid for.
Spree Commerce
This platform enables you to have your store customised to differentiate yourself from competitors and provides support to 50 plus payment gateways, thereby saving effort and time of merchants.
OpenCart
Helps creating unlimited categories, selling unlimited products, accepting multiple currencies with choice of 8 shipping and 20 payment methods. Being user-friendly and having SEO ensures top listing in Google.
VirtueMart
Designed for working with Joomla, this cart has the ability to make customers instantly comfortable. Having 2.5 million users till date, most have been satisfied about its performance.