Autodesk Developer Network

Frequently Asked Questions

1. What versions of ObjectARX are available?

You can download ObjectARX® software for the latest three releases of AutoCAD® and AutoCAD® for Mac® software products.

2. How do I get the ObjectARX software development kit (SDK)?

The complete ObjectARX SDK and license agreement are available for download at no charge. The SDK is not available on a CD.

3. What is the difference between RealDWG and ObjectARX for AutoCAD?

The RealDWG™ application is a subset of ObjectARX and contains the APIs for reading and writing DWG™ and DXF™ files. RealDWG does not contain support for viewing and accessing the AutoCAD user interface.

ObjectARX applications always require AutoCAD as their host application. RealDWG does not require the presence of AutoCAD software. RealDWG can be used to create independent host applications. ObjectARX cannot.

4. What documentation is available for developing applications in ObjectARX?

The following publications are included with the ObjectARX SDK:

  • Managed Class Reference
  • ObjectARX Developer’s Guide
  • ObjectARX Reference
  • Application Interoperability Guidelines
  • ObjectARX 64-bit Migration Guide

Links to other valuable developer reference materials are listed at

5. Is developer support or training available for ObjectARX?

Yes. Support is available through the Autodesk public forums ( or through membership of the Autodesk Developer Network ( ObjectARX training material is available for download from

6. Do I have to rebuild my older AutoCAD applications to work on the latest version of AutoCAD?

Applications developed using ObjectARX 2017 need to be recompiled for use with AutoCAD 2018-based products. Applications built with ObjectARX for the current release of AutoCAD (2018) will not work on earlier AutoCAD releases. Note that the DWG format has also been updated for the AutoCAD 2018 release.