Open CASCADE Technology (OCCT)
Open CASCADE Technology (OCCT) is an open-source geometric modeling kernel originally developed by Matra Datavision (France) as CAS.CADE and released under an open-source license in 1999. OCCT implements full B-rep solid modeling, NURBS surfaces, and standard CAD data exchange formats (STEP, IGES, STL). It is the kernel inside FreeCAD, Salome, and dozens of academic and industrial CAD tools, and its French origin makes it the canonical European alternative to Parasolid and ACIS.
Why it matters
OCCT represents Europe's distinctive contribution to the geometry-kernel layer of the PLM stack: an open, community-governed foundation rather than a proprietary licensed component. Its existence enabled a generation of European engineering software companies to build CAD and simulation tools without paying per-seat kernel royalties, and its governance model influenced how Dassault Systèmes positioned CATIA's modeling engine as an open platform inside the 3DEXPERIENCE ecosystem.
External References
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Cite this definition
Finocchiaro, Michael. “Open CASCADE Technology (OCCT).” DemystifyingPLM PLM Glossary, 2026, https://www.demystifyingplm.com/glossary/open-cascade-technology-occt