Although not implemented as MPW tools, the package also came with several source-level debuggers through its history; SourceBug and SADE (Symbolic Application Debugging Environment) were used on MC680x0 systems, while the Power Mac Debugger (known during development as R2Db) provided both local and remote debugging services for PowerPC systems, the latter by using a server program known as a "debugger nub" on the computer being debugged.