We at IndiWork have been working with Opencart since its startups days and we implement several website and complex custom extensions. OpenCart is considered best open-source eCommerce platform available today.
In our extensive experience using OpenCart framework in developing an e-commerce website, the framework offers a powerful, MVC architecture, xHTML compatibility, SEO friendly features that have inbuilt like custom titling, product-based URLs & canonical categories. Also comes with in depth powerful administration for easy to manage products, customers, orders, taxes rules, coupon codes and more.
Above all there is an excellent support free community and by being IndiWork customer you are entitled to dedicated support. To Learn more about Opencart.