perf Profiler for GNU / Linux with performance calculation. https://perf.wiki.kernel.org/index.php/Main_Page gdb GNU debugger that allows you to "spy" what is happening inside the program during its execution. https://www.gnu.org/software/gdb/ flame graph A graphical profiler. http://www.brendangregg.com/flamegraphs.html strace Used to diagnose and debug programs under GNU / Linux https://strace.io/