 <p>To add to other answers (obviously GDB...), <a href="http://lldb.llvm.org/" rel="nofollow">LLDB</a> is BSD-style licensed which is more permissive. It is part of the <a href="http://llvm.org/" rel="nofollow">LLVM Compiler Infrastructure</a>. is very similar to GDB (see a <a href="http://lldb.llvm.org/lldb-gdb.html" rel="nofollow">comparison</a>). </p> <p>Following your edit: it is not ready for windows yet but efforts are under way so it should be soon.</p>