© 2018 IEEE. A novel and widespread business model in cloud computing is to provide on-demand software as a service (SaaS) over the Internet. The software runs on a server and the user access it through an Internet connection. A single application instance can be shared by multiple users which provide a cost-effective solution to SaaS providers. Varying requirements from multiple users increase complexity in SaaS application design. The success of SaaS depends on its design. SaaS is different than traditional web-based application, so traditional application design model cannot full fill many SaaS specific design requirements. This paper provides a better understanding of key design factors in SaaS development process which results in a successful SaaS product following an improved design process. This study identifies key design factors through literature review and provides guidelines for key design factors on the SaaS application development. Ultimately, it will be beneficial for SaaS developers to improve the SaaS application development process and have a positive impact on the final product.