We currently use nopCommerce which is a fully customizable shopping cart. It's stable and highly usable. nopCommerce is an open source e-commerce solution that is ASP.NET 4.5.1 based with a MS SQL 2005 (or higher) back-end database. It has everything you need to get started in selling physical and digital goods over the Internet. We can customize and enhance the ASP.net web forms Version 1.9 or the ASP.net MVC framework version 3.60 or higher. We are recognized as a "Solution Partner" for the nopCommerce cart and application.