As a web applications developer, your main duties are to work as part of a development team to design functional, scalable applications for use on a website or mobile operating system. A web app developer needs to have a strong grasp of coding, graphic design, and user experience, as well as a firm understanding of how front-end code and back-end frameworks interact to ensure that web applications run properly on the company servers. In addition to technical responsibilities, you also consult with clients or other departments to determine their needs and how best to address those needs via the app.