API Monitor!

Valgrind is an instrumentation framework for building dynamic analysis tools. There are Valgrind tools that can automatically detect many memory management and threading bugs, and profile your programs in detail. You can also use Valgrind to build new tools.

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.

WinAPIOverride is an advanced api monitoring software for 32 and 64 bits processes. You can monitor and/or override any function of a process. This can be done for API functions or executable internal functions.

JTracer is a remote debugger client for the Libcsdbg debugger

SpyStudio is the best product to trace user-mode API calls on Windows. SpyStudio is an Application tracer which shows and interprets calls, displaying the results in a structured way which is easy for any IT professional to understand. SpyStudio can understand the resources that an application uses, track down errors, detect malware and create application layers for virtualization.SpyStudio has a trace comparison tool which is useful for identifying problems in virtualized environments. You can obtain two samples: the native version of the application and the virtual version which has the problems. Using the 'Compare traces' feature, you can see what is missing in the virtual environment. SpyStudio is the user-mode SysInternals Process Monitor's (aka Procmon) complement. Looking for application errors with kernel-mode traces is tedious, and it is very difficult to see the final outcome of a user-mode call. With kernel-mode tools, you get a lot of noise that the application does not see, since a single user-mode call generates lots of kernel-mode events that are not important from the application's perspective. Most application errors are generated by failed user-mode calls which expect a different state of some resources: registry keys and values, files, pipes, services and printers.SpyStudio is also able to load and interpret Procmon logs. »

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.

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) »