A Heavy Backend Experience developer primarily focuses on server-side web application logic and integration of the work front-end developers do. They build and maintain the technology that powers those components which, if combined together, enable the user-facing side of websites to even exist. Their work includes writing APIs, creating libraries, and working with system components to ensure smooth data exchange. They often deal with databases, scripting, and website architecture. They design and implement data storage solutions, optimize output to match system requirements, and troubleshoot applications and systems for better performance and capacity.