Building an e-Commerce website is an end-to-end project that certainly involves web design. A better user-experience (UX) translates to better conversions, and web design plays a big part in UX. However, there are cases where a web agency takes on a heavy development role such as ERP, and API integration only. Examples of metrics to measure ecommerce project success are website design, e-Commerce platform, functionality & user-friendliness, data use, digital marketing and SEO, 3rd party app integration, shipping, responsive design.