The backend developer specialises in design, implementation, functional logic and performance of a system that runs on a machine which are remote from the end-user. The back end of a website is made up from a server, application and a database and a back-end developer helps to build and maintain these components. By doing this they are enabling user-facing side of a website to exist. Their development skills are Java, C++, Ruby, Python, Scala and Go.
Mobile developers write codes for applications that run on mobile devices such as tablets and smartphones. Mobile developers only started to become popular after the boom of mobile devices in the early 2000s and the growth of the smartphone market. A mobile developer understands mobile operating systems such as iOS and android and the environment and frameworks used to create software on these systems. They have a variety of development skills, such as Java, Swift, Objective-C, Application Programming Interfaces, web development languages and cross platform mobile suites.