A Blackbox developer is responsible for testing software functionality without understanding its internal structure or coding. They simulate user interactions to identify any issues or bugs, ensuring the software behaves as expected under various conditions. Their work includes designing test scenarios, executing test cases, and documenting results. While they don't need to know the internal workings of the software, they must have a clear understanding of the software requirements and user expectations. Their primary goal is to validate the software's functionality and usability, helping to deliver a high-quality product to the end-user.