A full-stack developer is a developer or engineer who can build both the front end and the back end of a website. The front end (the parts of a website a user sees and interacts with) and the back end (the behind-the-scenes data storage and processing) require different skill sets. Control all technical, functional, and visual aspects of the software in progress. Adapting the application to various devices. Software optimization. Ensuring the design works well with the functionality of the finished product. Full-stack developers are experts in both the frontend and backend; so, the full-stack of technology that makes up a website. They are proficient in both frontend and backend languages and frameworks, as well as in server, network and hosting environments.