OCCT3D Open Source

Be free with your 3D modeling kernel

Open CASCADE Technology (OCCT) is an open-source C++ platform for building 3D CAD, CAM and CAE applications. It provides production-grade components for geometry and topology, solid and surface modeling, visualization, data exchange and application data management. Teams can use the complete platform or integrate only the toolkits required by their product. OCCT is available under the GNU Lesser General Public License (LGPL) with the OCCT exception.

View OCCT on GitHub

Core Capabilities

Modeling & Geometry

Parametric 3D solid modeling
NURBS curve and surface modeling
Boolean operations
Fillets, chamfers and construction features
Geometric algorithms

Visualization

High-performance 3D rendering
Interactive view manipulation
Selection and highlighting
Clipping and hidden-line presentation
Customizable display pipeline

Data Exchange

STEP, IGES, STL and BREP import/export
Mesh data handling
XDE support for assemblies, names and colors
Shape healing tools

Application Framework

OCAF document architecture
Transactions and undo/redo
Application data attributes
Assembly and product structures with XDE
Data persistence

Ideal Applications

OCCT provides the technical foundation for specialized CAD/CAM/CAE applications, including:

FEA pre/post-processors CNC/CMM path generation Engineering simulation Specialized CAD tools Medical imaging Architecture modeling Design automation Digital twins

Proven Technology

Open CASCADE Technology has been continuously developed since the mid-1990s. It is used as a technical foundation for open-source and commercial engineering applications across industries ranging from software development to manufacturing.

As an open-source alternative to proprietary modeling kernels, OCCT gives development teams direct access to the implementation and the flexibility to integrate only the components required by their products.

Comprehensive Documentation

OCCT Documentation C++ API Reference

Join the Open Source Community

OCCT is developed in public. Developers can discuss implementation questions, report reproducible issues, submit fixes and new functionality, improve documentation, and share experience from OCCT-based projects.

How to Get Involved

01Contribute code improvements, corrections or new features

02Participate in technical discussions on the forums

03Share information about OCCT-based projects

04Request dedicated forums for significant community projects

05Report and help fix bugs to improve stability

Visit the OCCT Developer Community

Why Choose OCCT3D?

OCCT combines an open development model with mature C++ components for geometry, modeling, visualization, data exchange and application data management.

Open Source (LGPL + OCCT exception)

Direct access to the source code and use in commercial applications under the license terms.

C++ Class Libraries

Native C++ performance and fine-grained control over integration.

Active Development

Regular releases, bug fixes, performance work and new functionality.

Developer Community

Public technical discussions, issue tracking, documentation and examples.

Professional Support Available

Architecture review, integration support, algorithm development and maintenance.

Ready to Start Building with OCCT3D?

Use the public source code and documentation, or contact OCCT3D for professional engineering support.

Get OCCT Discuss Engineering Support