There are plenty of built-in performance/introspection tools in OS X that you can try first before resorting to a third-party solution: 1) What ports it opens:

There are plenty of built-in performance/introspection tools in OS X that you can try first before resorting to a third-party solution: 1) What ports it opens: - netstat shows you what ports a program has running - DTrace shows you all syscalls a process makes (among other things). dtruss is a convenient wrapper script included in OS X which shows you all the syscalls a process makes (including opening sockets. 2) What files it opens - Again, DTrace's syscall provider lets you introspect all syscalls, including open(). There's even a handy wrapper script included with OS X called opensnoop. - Alternately, you can use the fs_usage command line tool to tap into the xnu kernel's trace mechanism. This shows all sorts of filesystem events, including what files are opened. 3) What libraries a binary is linked to OS X binaries use the Mach-O format, not ELF like most other Unixes. So you have to use OS X's binary introspection tools to understand that format rather than the standard GNU binutils. What you're looking for here is otool, which lets you introspect Mach-O binaries. Specifically, "otool -L /Applications/Mail.app/Mail" for instance shows you which libraries Mail links to. Run this recursively to get the transitive closure of all dependencies a binary links against. Another way to do this is to run "vmmap -v <pid>" to show you the vm layout of a process, which includes the __TEXT/__DATA segments of all libraries the process links against. And of course, gdb/lldb is included with the developer tools, you can just attach to whatever process you care about and set breakpoints, type "info sharedlib" to see what libraries are in the address space, etc. Also, for better or worse, Objective-C is an extremely dynamic language, so you can even do things like write a shared library with code you want to inject into a process (potentially monkey-patching existing methods using ObjC categories) and dlopen it from gdb to insert it into the target process's address space.