Here are lists of free ecommerce Contents Management System (CMS) you can use for free to build your own eCommerce, online store to selling products. Majority of them are built by the open source community, which means you can download and use them for your own online store.
All of these e-Commerce CMS have strong community support, easy installation, support some kind of payment gateway and has many successful deployment around the world.
Some of these open source can be installed using a script installer like cPanel or Softaculous commonly found in professional web hosting. A note of cautious though, different web hosting have different options available in them.
1. Open Cart
"A powerful open source shopping cart system that is designed feature rich and user friendly", a robust eCommerce solution for internet merchants with the ability to create their own online business and participate in eCommerce at a minimal cost.
Has community support forum, blog news, support multiple currency, multiple language etc. You can find all its latest features at their features page - features
You can download a copy of Open Cart at Open Cart download
2. Presta Shop
"Build your online store", Sell online with Presta Shop's free, secure and open source shopping cart platform is the headline from presta shop
With more than 275 features, over 2000 modules and templates, over 100,000 worldwide installations and available in more than 40 languages are the highlights features of Presta Shop.
You can dowload a copy of the free version at Presta Shop download (English version).
The Art of E-commerce - putting the dream of online business ownership within reach of anyone! Has a support forum that has over a million threads and more than 100,000 members.You can download copy of Zen Cart at Zen Cart download
4. OS Commerce
The Open Source E-commerce Solution - has many backend and frontend functionality, you can find a copy of the latest version for free download and up-to-date functionality at OS Commerce features
Has been around more than 10 years and have over 12,700 online shops worldwide.
"Easy shopping cart" for online business. Drive your sales with Avactis. Paid and free version of shopping cart available. Allow a potential customer to upgrade without lossing any data. The free version include Paypal as the only payment getway whereas the paid versions includes over 40 payment getways.
Besides the free version, the premium categories include are "Owned", "Monthly lease", "White label" and "Premium". You can find detail features comparison between the free and paid version at Avactis Editions differences
You can get the download link to the free version, at their official website after signing up with an email.
Ecommerce Platform for Growth. One of the most professional looking ecommerce around with plenty of paid developer taking on jobs.
One very enticing feature Magento has, is their showcasing of world brand known to be running their application. You can take a look at Magento showcase
The only support forum that support multiple language.