Shopify

An eCommerce storefront engine that provides marketing analytics, shipping discounts, and several other back-end services for online entrepreneurs

Square E-Commerce (formerly Weebly)

Pay for online purchases or in-person purchases with a smartphone instead of a physical card

BigCommerce

A rich eCommerce storefront engine with embedded marketing analytics, shipping services, and enterprise-grade shopping cart features

Ecwid

Sales enablement software that lets eCommerce businesses sell directly on Twitter, Facebook, YouTube, and Instagram

FastSpring

An e-commerce partner designed for global companies, making it easy to compete with ads and conversions

Miva

Efficient eCommerce platform that integrates with almost any kind of business model

2Checkout

Payment processing service designed for small businesses for portable usage

Magento Open Source

Free eCommerce system designed to allow individuals and organizations to run their own online store

nopCommerce

Open source ecommerce solution for any business of any size

Digital River MyCommerce

A cloud SaaS e-commerce solution that handles different payment and billing duties for a business