Data protection is often a sacrifice that companies are willing to make in order to use very user-friendly software, only because all the needs of the client are not specified in advance. If you agree in advance with the developers about everything, then they will be able to provide a reliable and secure SaaS product. For example, I worked with these developers https://devoxsoftware.com/services/saas-development-company/ , and I can’t say anything bad about them. They helped me with the design of the SaaS architecture and also did some testing and QA.