There are many e-commerce open source framework available in PHP like Magento, Prestashop, Open Cart, OS Commerce etc. But in ASP .NET some calculated e-commerce open source framework available. We are listed it. You can see it below
nopCommerce is open-source ecommerce solution. It's stable and highly usable. nopCommerce is an open source ecommerce solution that is ASP.NET (MVC) based with a MS SQL 2008 (or higher) backend database. Our easy-to-use shopping cart solution is uniquely suited for merchants that have outgrown existing systems, and may be hosted with your current web host or our hosting partners. It has everything you need to get started in selling physical and digital goods over the internet. nopCommerce offers unprecedented flexibility and control.
Link : www.nopcommerce.com
dashCommerce is a flexible and robust ASP.NET Open Source e-commerce application that you can use to set up your online store. dashCommerce has been available since early 2008 and has been used in countless online stores and is wildly successful.
Link : www.dashcommerce.org
SmartStore.NET is a free, open source, full-featured e-commerce solution for companies of any size. It is web standards compliant and incorporates the newest Microsoft web technology stack.
SmartStore.NET includes all essential features to create multilingual and multi-currency stores targeting desktop or mobile devices and enabling SEO optimized rich product catalogs with support for an unlimited number of products and categories, variants, datasheets, ESD, discounts, coupons and many more.
A comprehensive set of tools for CRM & CMS, sales, marketing, payment & shipping handling among others makes SmartStore.NET a powerful all-in-one solution fulfilling all your needs... totally FREE!
Link : www.smartstore.com/net/en
Kartris is an ASP.NET e-commerce application that features a CMS catalog system, shopping cart, payment systems and full administration back end. It is designed to run on Microsoft's IIS web server, and exploits the powerful caching and optimization features of that platform.
DotShoppingCart combines ecommerce with the powerful content management publishing tools. The pluggable modularized architecture meets all your needs to create and manage your web sites. Whether it's a personal blog, family Web site, or ecommerce business, DotShoppingCart is the best one stop shop software for building web site.
AspxCommerce offers a complete e-Commerce solution that allows you to build and run your fully functional online store in minutes. You can create your storefront; manage the products through categories and subcategories, accept payments through credit cards and ship the ordered products to the customers.
Link : www.aspxcommerce.com
Suteki Shop is an eCommerce application. The orginal aim is to write a site for a fashion retail business. It includes a product catalogue, shopping cart and order processing.
Link : www.code.google.com/p/sutekishop
We listed above e-commerce ASP ,Net Frameworks. It will very helpful to you to develop faster way e-commerce site in ASP .Net. If you know more frameworks then comment it.