A LINQ developer is responsible for integrating and managing data using Language Integrated Query (LINQ) in .NET programming. They write LINQ queries to interact with data sources like SQL, XML, and in-memory collections, enabling seamless data manipulation and transformation. Their role includes designing, developing, and optimizing these queries to ensure efficient data retrieval and manipulation. They also troubleshoot and resolve issues related to data access and performance. Furthermore, they collaborate with other developers to integrate LINQ queries into larger .NET applications, thereby facilitating streamlined and reliable data operations.