API Monitor is described as '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' and is an app in the Development category. There are nine alternatives to API Monitor for a variety of platforms, including Linux, Windows, Mac, Android and BSD. The best alternative is Process Monitor, which is free. Other great apps like API Monitor are Valgrind (Free, Open Source), SpyStudio (Free), ApproveAPI (Paid) and strace (Free, Open Source).
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.
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.
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.
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.
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.