An IBM Rational Purify developer primarily focuses on using the IBM Rational Purify software to detect and debug errors in programming code. They identify memory leaks, access violations, array bounds violations, and uninitialized memory usage, ensuring optimal performance of software applications. These developers also work on memory profiling to examine how much memory an application is using and for what purposes. They conduct runtime analysis to pinpoint hard-to-find bugs and ensure the reliability, efficiency, and accuracy of software applications. They also play an integral role in software development, testing, and maintenance processes.