A .NET CLR (Common Language Runtime) developer designs, develops, and maintains software applications using Microsoft's .NET framework. They work on CLR, a runtime environment that handles the execution of .NET programs, ensuring interoperability across different programming languages. Their tasks include memory management, garbage collection, exception handling, and thread management. They also manage code execution, type safety, security, and performance to optimize application functionality. Additionally, they ensure that .NET applications are compatible across different platforms. They also collaborate with other software developers to debug and improve software applications.