IntelliCAD

IntelliCAD is a CAD editor and development platform with an Application Programming Interface API published by the IntelliCAD Technology Consortium ("ITC") through shared development. IntelliCAD emulates the basic interface and functions of AutoCAD, however, it is particularly able to incorporate and interchange freely between a wide variety of file types (i.e. dwg., BIM, TIFF, etc.). 
ITC IntelliCAD is not sold directly to end users but is licensed to consortium members who support the shared development by paying annual fees, similar to a co-op arrangement, in exchange for permission to distribute IntelliCAD-based solutions worldwide with their own end-user license agreements.
IntelliCAD Technology Consortium.
Founded in 1999, the IntelliCAD Technology Consortium ("ITC") is the international, non-profit organizational body that develops the IntelliCAD engine and development platform for its members. The ITC also develops integrations with third-party technologies, such as the "ODA Platform" from the Open Design Alliance which it uses for working with “.dwg”, Building information modeling (BIM), and DGN data formats.
The ITC supports interoperability and is a founding member of the Open Design Alliance. The ITC is registered in the state of Washington in the US, and its corporate headquarters are based in Portland, Oregon, USA.
IntelliCAD Functionality.
IntelliCAD's native format is .dwg and it has a set of commands similar to AutoCAD by Autodesk. IntelliCAD can also natively open and edit MicroStation DGN files by Bentley Systems.
Included in IntelliCAD functionality:
IntelliCAD is available for Microsoft Windows desktops.
History.
Early 1990s
"IntelliCADD" began as an independent AM/FM/GIS (Automated Mapping/Facilities Management/Geographic Information System)
software firm in La Mesa, CA, USA. One of its products, AutoCAD Data Extension, allowed multiple users to access the same AutoCAD drawing, or have a single drawing point to entities stored in other drawings. Softdesk, the then-largest third-party product developer for Autodesk, acquired this company in 1994 and used the know-how to secretly develop an AutoCAD clone. Autodesk had recently entered into direct competition with Cyco Software (another third-party Autodesk partner), and Softdesk was concerned that the same could happen to them. The AutoCAD-clone project was kept semi-secret under the project name ""Phoenix"."
1996-1998
In December 1996 Autodesk announced that it would acquire Softdesk outright for $90 million in common stock. A complaint regarding the inclusive sale of IntelliCADD was filed with the US Federal Trade Commission ("FTC"). According to FTC Docket No. C-3756:
By late 1996 a formal search for new venture capital was underway. Marketing director Robert Drummer was referred to John Forbes at Visio Corporation and "gave him the pitch". Further according to his own first-hand account, "He (John Forbes) called back a few hours later and said that he along with Jeremy Jaech and Ted Johnson would be chartering a plane that day and would be down to take a look at a demo. They arrived in San Diego that evening." A core team of nine Softdesk/IntelliCADD developers soon moved to become employees of Visio. In March 1997 the FTC forbade "Autodesk or Softdesk from re-acquiring the IntelliCADD product or any entity that owns or controls it, without prior notice to the Commission for a 10 year period". The FTC granted Visio leave to acquire Boomerang completely for $6.7 million in the same ruling that prevented Autodesk from doing so (above). IntelliCAD's original architect, Mike Bailey, turned and left Visio before the first release. Nevertheless, after several years of background development, "Visio IntelliCAD" (one 'D' for the product, two for name of the original company) was finally released for the first time to the public in 1998 with a very low price compared to AutoCAD. Twelve thousand licenses of IntelliCAD were sold in the first three months before new concerns over software stability emerged.
Visio's "IntelliCAD 98" sold about 30,000 copies—far less than some expected. IntelliCAD development seemed to need more resources than Visio could grant it. At this point, Visio "granted a royalty- free, perpetual license for the IntelliCAD (2000 version) source code to The IntelliCAD Technology Consortium".
1999
On September 15, 1999 Microsoft announced that it would acquire Visio Corporation (completed in January 2000)—a deal that evidently included Visio's "IntelliCAD 98". A new IntelliCAD 2000 source code branch, however, continued independent development under the new ITC.
Early 2000s IntelliCAD 3 ("IntelliCAD 2001") introduced complex linetypes, XREF clipping and IntelliCAD's first display and printing of ACIS 3D solids on May 22, 2001. IntelliCAD 4 released with full ACIS 3D solid modelling in 2003. IntelliCAD 5 added workspaces with tabs and DWF file support in October 2004. ITC announced a new partnership with SolidWorks, which added tabbed workspaces and DWF support.
Mid 2000s IntelliCAD 6 added True Color color support (16 million colors), ADeko Raster raster image support tool, previewing thumbnails while viewing drawing files, drawing and viewing elements, and attaching WAV files as audio notes in November 2005.
Late 2000s During the 2008 ITC meeting in Athens, Greece, the first test release of IntelliCAD 7 was announced with a complete replacement of the old ITC internal database and the old "SDS" API with newer DWGdirect and DRX APIs from the ODA. In 2009, about 50 ITC members globally shared in IntelliCAD development. Work continued on IntelliCAD 7 while simultaneously releasing IntelliCAD 6.1 through 6.6 over the next several years.
2011 The complete replacement of the old ITC internal database was released as IntelliCAD 7 in June of 2011.
2014 IntelliCAD 8 was released on June 13, 2014 for 64-bit and 32-bit versions and allowed opening, saving and creating *.dwg files of the 2014 file format. New features included layer states, search layer filters, layer transparency and window freezing, custom menu *.cui files, quick selection, 3D orbits, additional mesh capabilities, Collada (.dae) file import, MrSID MG4 compressed raster image support and more. IntelliCAD 8.0 included Teigha® Open Design Alliance (ODA) version 3.9.1 and VBA 7.1 support. The source code for advanced rendering and image processing components was made available to all ITC members.
2017 At the 2017 conference in Aukland, New Zealand, IntelliCAD as a native .dgn file editor was announced. IntelliCAD 8.4 was released in July 2017 and included the ability to attach IFC files as underlays.
2018 IntelliCAD 9 included native support for opening, editing and saving *.dwg 2018 file versions, incremental saving to increase performance, Mechanical entity support, tool palettes, and issues related to running IntelliCAD on Fall Creators 2017 Microsoft® Windows® 10 were also fixed. IntelliCAD 9 also included the ability to work with data from .rvt/.rfa files (Autodesk Revit files) and import IFC files as architectural entities. Released in June 2018. 
2020 IntelliCAD 10 included import of Wavefront Technologies Object (.obj) files, import and export of Stereolithography (.stl) files, dynamic input, migrate user interface customizations, and clickable keywords. Released in July 2020. 
Software based on IntelliCAD.
Some of the software that is based on IntelliCAD:
IntelliCAD is used in these industries: 