Net-dbx-G is a tool that utilizes Java and other World Wide Web tools as an interface to Grid services to help Grid application developers debug their MPI programs from anywhere in the Internet. Net-dbx-G is a source level debugger with the full power of gdb (the GNU Debugger), providing the user with full Grid functionality. The portability of the tool is of great importance as well because it enables the tool to be used on heterogeneous nodes that participate in an MPI enabled, Grid environment. The users of our system simply point their browser to the Net-dbx-G webpage and authenticate to the virtual organization that they are part of. Having at their disposal the shared resources participating with that VO, they start debugging by interacting with the provided GUI environment of the tool. The users can dynamically select which MPI processes to view/debug.