For most suppliers and retailers, the out-of-the-box functionality provided by ecommerce vendors is enough. Developers are needed if you want to customize ecommerce for some kind of non-standard business processes. In general, it does not matter whether the software is installed on the server in the data center (i.e., in the cloud) or on-premises. It should be noted that the software provided according to the SaaS model cannot be modified by developers on the client's side. The SaaS vendor does not provide third-party developers with access to the code for such an application.