Valgrind!

API Monitor is a Windows program that lets you monitor and control API calls made by applications and services. Its a powerful tool for seeing how applications and services work or for tracking down problems that you have in your own applications.

JTracer is a remote debugger client for the Libcsdbg debugger

Libcsdbg is a C++ exception stack tracer. When an exception is thrown, caught and handled, libcsdbg offers the tools to create and process the exception stack trace, the path the exception has propagated up the call stack, unwinding it, up to the section were it was handled. The traces are detailed with demangled function signatures and additional addr2line info (the source code file and line that each function was called). Libcsdbg will perform flawlessly with single and multi-threaded (or multi-process) programs, with any dynamically linked shared object (DSO - Dynamic Shared Object) and with any statically linked library. Additionally, libcsdbg helps the developer/tester create sophisticated stack traces of any thread, at any given moment during a process execution, as a snapshot of the runtime call graph. This is very useful in cases of fatal errors, reception of terminating signals or process abortion/termination (such as segmentation faults) »

Dr. Memory is a memory monitoring tool capable of identifying memory-related programming errors such as accesses of uninitialized memory, accesses to unaddressable memory (including outside of allocated heap units and heap underflow and overflow), accesses to freed memory, double frees, memory leaks, and (on Windows) handle leaks, GDI API usage errors, and accesses to un-reserved thread local storage slots.

strace is a diagnostic, debugging and instructional userspace utility for Linux. It is used to monitor interactions between processes and the Linux kernel, which include system calls, signal deliveries, and changes of process state. The operation of strace is made possible by the kernel feature known as ptrace.

Deleaker is a useful extension for Visual Studio 2005, 2008, 2010, 2012, 2013 that helps you to analyze programming errors, many of which are unique to Visual C++. Deleaker is a great tool for Visual C++ developers who occasionally have trouble detecting resource leaks and debugging their applications. With Deleaker, you can detect and localize resource leaks in memory, GDI and USER objects, handles, with no appreciable slow down to your application.

ltrace intercepts and records dynamic library calls which are called by an executed process and the signals received by that process. It can also intercept and print the system calls executed by the program. Used for debugging.