A Borland C++ Builder developer designs, codes, tests, and debugs software applications using the Borland C++ Builder, a rapid application development environment. They create user-friendly interfaces, write efficient codes for functionality, and troubleshoot any issues that arise during the development process. They also ensure the software is compatible across different platforms and devices. Developers may work on a variety of projects, from creating desktop applications to developing complex system-level software. They also document their code and processes, collaborate with other team members, and stay updated on the latest industry trends and technologies.