A GDB and Valgrind debugging tools developer creates and maintains software tools used to analyze and debug other software applications. They use GDB (GNU Debugger) to inspect and control the execution of programs, examining variables and call stacks, setting breakpoints, and changing variables to test different conditions. With Valgrind, they detect memory leaks and concurrency issues, ensuring efficient memory usage and thread-safety in programs. The developer must understand complex software systems, problem-solving, and debugging strategies. They also need to keep up with new programming languages and techniques to ensure that the tools remain useful and effective.