strace!

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.

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.

Sysdig is open source, system-level exploration: capture system state and activity from a running Linux instance, then save, filter and analyze. Think of it as strace + tcpdump + lsof + awesome sauce.With a little Lua cherry on top.

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) »

DTrace is a performance analysis and troubleshooting tool that is included by default with various operating systems, including Solaris, Mac OS X and FreeBSD. A Linux port is in development.

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.

Ftrace is an internal tracer designed to help out developers anddesigners of systems to find what is going on inside the kernel.It can be used for debugging or analyzing latencies andperformance issues that take place outside of user-space.

ktap is a script-based dynamic tracing tool for Linux. It uses a scripting language and lets users trace the Linux kernel dynamically. ktap is designed to give operational insights with interoperability that allows users to tune, troubleshoot and extend the kernel and applications. It's similar to Systemtap and DTrace.

The ktrace utility enables kernel trace logging for the specified processes. Kernel trace data is logged to the file ktrace.out. The kernel operations that are traced include system calls, namei translations, signal processing, and I/O.

SystemTap provides free software (GPL) infrastructure to simplify the gathering of information about the running Linux system. This assists diagnosis of a performance or functional problem. SystemTap eliminates the need for the developer to go through the tedious and disruptive instrument, recompile, install, and reboot sequence that may be otherwise required to collect data.