Due to the expansion of new markets, accessible technologies, and venture funding, software startup growth is amazing. Moreover, startups are frequently required to adapt their software products prior to deployment at a customer's location. The authors collected a data set of 30 software projects retrieved from three software businesses using a case study research approach, with each software startup supplying a data set of 10 of its software projects tagged as failure projects in their project repository. The authors quantify and demonstrate the level of substantial software customization in startup software projects. The authors have also presented a simplified technique for quantifying customization requests for startups. Additionally, they offer tips and best practices to assist entrepreneurs in managing software customization.