A business-logic developer designs, implements, and maintains the server-side aspects of web applications. They focus on algorithms and data management, ensuring the seamless exchange of information between servers and users. They work closely with front-end developers and use languages such as Python, Java, or C# to create the business logic, which is the core computational part of any software. Their duties also include debugging, troubleshooting, and improving the efficiency of existing systems. They must understand the business requirements and translate them into effective code, playing a crucial role in aligning technology with business strategy.