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. To sum up, a full-stack designer is someone who takes part in every aspect of the product design process, from initial idea generation to final implementation, including but not limited to project planning, sales strategy, market analysis, UX design, user interface design, and perhaps writing codes.