The Nokia Developer Platforms enable us to develop portable and scalable mobile applications for hundreds of millions of Nokia devices. In this chapter, we covered the Series 40 and 60 Developer Platforms and introduced the four enabler technology pillars. They are WAP, MMS, J2ME, and Symbian C++. We reviewed the application paradigms each technology enables and discussed their strengths and shortcomings. It is crucial for us to understand those technologies and know how to apply them correctly to suit specific application needs. Near the end of this chapter, we also covered Nokia's developer support programs that connect developers to volumes, answers, and customers.