GlobalCAD  
   Offers general drafting tools as well as LandARCH, a landscaping application for AutoCAD.
   http://www.globalcad.com/products/index.html

Struc Plus  
   Suite of parametric driven modules that provide tools and macros related to the preparation of structural engineering drawings.
   http://www.struc-plus.com/

ATG CCM Plus 2000  
   Software for accessing and editing facility management data in AutoCAD with an integrated MS Access interface.
   http://www.ccmplus.com/

InAdire Teknik  
   Free and commercial AutoCAD LT and MicroGDS add-ons for drawing reinforcement bars and insulation.
   http://www.inadire.se/

MBA Computing  
   Timber Frame software for the housing and construction industries. Products consist of Construction Designer Modules, as well as training and consultancy.
   http://www.mbacomp.demon.co.uk/

ArchSymb  
   Architectural symbols and routines for AutoCAD [requires Javascript for navigation].
   http://www.archsymb.com/

Leica Geosystems TPS-CAD  
   An online data acquisition application for use with AutoCAD and the LEICA TPS300 Series Total Stations.
   http://www.leica-geosystems.com/surveying/product/software/tpscad.htm

FireAcad Design Software  
   AutoCAD extension for fire sprinkler designers. The program aids in design, hydraulic calculations and material listing.
   http://www.fireacad.com/

AC Plant Designer  
   A plant design and construction toolkit connecting AutoCAD with database functionality.
   http://www.acplant.com/

ArchSoft  
   A 2D application program for AutoCAD and IntelliCAD for producing architectural working drawings.
   http://www.grovetec.com/

Cad Easy Corporation  
   AutoCAD extensions EasySite for terrain modelling and visualization, and EasySurf for mapping and road development, as well as related symbol libraries.
   http://www.cadeasy.com/

LTplant  
   Electrical, instrumentation, and plant design software for AutoCAD LT, with isometric drafting and BOM functionality.
   http://www.ltplant.com/

Stardsign CAD Solutions  
   Extensions to Architectural Desktop offering utility functions, dormer construction, and layer management.
   http://www.stardsign.com/

Survey, Cogo and Drafting  
   Surveying, coordinate geometry, digital terrain modelling, and drafting applications for Intellicad and AutoCAD, as well as free autolisp routines.
   http://www.CogoSoftware.com/

Computer Services Consultants Ltd.  
   Manufacturers of the 3D+ parametric 3D structural modeling and drawing application with integrated analysis and design.
   http://www.3dplus.info/

Design Master Software, Inc.  
   HVAC and electrical building design and drafting software for AutoCAD.
   http://www.designmaster.biz/

SteelTools  
   Application for steel detaling in AutoCAD, with automatic bill of materials.
   http://deterset.homeip.net/SteelTools/

Roof Builder Tools  
   A 3D roof modelling shareware for AutoCAD.
   http://www.roofbuildertools.com/

AB Studio  
   CADCON is an extension to AutoCAD or Architectural Desktop for structural and building services design.
   http://aec.cadkon.cz/

Inopso GmbH Interoperable Solutions  
   Offers an IFC-Interface for Architectural Desktop, which allows to exchange architectural data according to IAI standards.
   http://www.inopso.com/

MultiSUITE Software  
   2D and 3D structural detailing software for concrete and steel. Use as stand-alone, with AutoCAD or AutoCAD LT.
   http://www.multisuite.com/

Advanced Graphics Technology, Inc.  
   Software for Cogo, legal descriptions, TIN models, contours, and sections, based on AutoCAD and LandDesktop.
   http://www.agtcad.com/

PERI GmbH  
   Offers the PERICAD AutoCAD extension and ELPOS for formwork planning with PERI Formwork and Scaffolding.
   http://www.peri.de/ww/en/pub/aktuelles/start.cfm