Forward: Open Source E-Commerce Platform
Forward is a developer-centric e-commerce platform which can be easily customised with coding, templates and expressive syntax. It has been developed as an alternative to the existing e-commerce CMSes that are way too complex to customise.
You can easily add some features or or customize the admin interface of your e-commerce store. It is developed with Twitter Bootstrap to make designing for the e-biz platform easy.
Forward e-commerce platform is scheduled for public release in 2013. The code will be 100% open source, so free forever.