ArxDbg is the name of a sample project that has been included with the ObjectARX SDK for many years. It’s primary purpose is to demonstrate how to use the ObjectARX API, but it is a complete free-standing utility in its own right. ObjectARX programmers often use this utility during development for testing and exercising their application code, but it can be useful to anybody, not just programmers.
As you can see, the UI consists of a single context menu. One of my favorite features is the ability to spelunk through a drawing database, looking at every object and its relationships to other objects. The command is ArxDbgSnoopDb, or you can select ‘Database Info…’ in the ArxDbg context menu.
There is no documentation, but anyone with a basic familiarity with the AutoCAD object model can figure out what most of the commands do. [Updated 2016-03-22] ArxDbg.zip [3.3 Mb] includes versions of the utility for all versions of AutoCAD from AutoCAD 2000 through AutoCAD 2017.