A Black Box Testing developer conducts tests on a system without knowledge of its internal workings. Their focus is on inputs and outputs, not the internal code. They design test scenarios, input data, and execute tests to validate functional requirements. They verify system behavior, identify bugs, and document test results. This approach ensures that the system functions correctly from a user's perspective, regardless of the internal logic. A Black Box Testing developer plays a crucial role in quality assurance, ensuring the software is free of defects and delivers the expected performance before it's released to the end-users.