AutoLISP
Atkinson Automation, AutoCAD LISP 2000, AutoLISP Programming, AutoLisp.Net, Autolisper, Better Than Nothing AutoLISP Programs, Martin Nigg, The Autolisp and Autocad Page, The AutoLISP Drawer, The LISP Generator
AfraLisp
Dedicated to the study of AutoLisp and VBA together with AutoCAD, including tutorials about both languages.
AJaX - the AutoCAD/Java eXtension
An open source project to integrate a Java2 VM into AutoCAD and to provide the necessary interfaces and class libraries.
ARX LT SDK
An extension to AutoCAD LT to enables the ObjectARX API as with the standard version of AutoCAD.
AutoCAD Developers Group Europe
A non-profit association of software developers who are working on applications around AutoCAD.
AutoCAD Exposed
Information about undocumented features of AutoCAD, such as commands, system variables, and functions of the ADS, ARX, and AutoLISP programming interfaces.
ObjectDCL
An interactive replacement of the DCL language for developing dialog boxes within AutoCAD, sold online.
OpenDWG Alliance
An association of CAD customers and vendors committed to promoting Autodesk's AutoCAD DWG drawing file format as an open, industry-standard format for the exchange of CAD drawings.
Py_acad
A free software module that makes it possible to extend AutoCAD with the Python programming language, in a similar way as with AutoLISP.
Ransen's ObjectARX Course
A multimedia based tutorial on programming ObjectARX on CD-ROM, with three of 20 chapters downloadable as a demo.
xarch AutoCAD Info and Tools
A resource for AutoCAD developers, including an AutoLISP standard library and the AutoLISP FAQ, as well as code examples in AutoLISP, ADS, and ARX. Visitors can add information in an AutoCAD Wiki.