GitHub repositoryModeling and geometry
Create, inspect, transform, and repair curves, surfaces, meshes, and boundary-representation models.
- Curves and surfaces
- B-rep topology
- Boolean and feature operations
- Meshing and shape healing
OCCT: open-source C++ platform
Open CASCADE Technology
OCCT (Open CASCADE Technology) is an open-source C++ platform for 3D modeling, visualization, CAD data exchange, and application development.
- 01Model and analyze geometry
- 02Present and exchange data
- 03Build the product layer
Release downloadsDownload OCCT
Download OCCT source code from GitHub. Choose a release below to find its source archives, release notes, and any additional packages provided for that version.
Download OCCT 8.0.17.x19 releases
A modular C++ platform
An open-source CAD kernel for C++ applications
Open CASCADE Technology, often written as OpenCascade, provides C++ libraries for geometry, B-rep topology, solid modeling, visualization, data exchange, and application data.
Teams can inspect the implementation, integrate at toolkit level, and keep their own product architecture around the open foundation.
Core capabilities
Modeling, visualization, exchange, and application data
Interactive visualization
Build desktop and embedded 3D experiences with presentation, selection, clipping, and rendering services.
- Interactive 3D views
- Selection and highlighting
- Hidden-line removal
- Materials and rendering
Data exchange
Move precise geometry, assemblies, names, colors, and attributes through established engineering formats.
- STEP and IGES
- Mesh and scene formats
- XDE assemblies and metadata
- Shared exchange wrappers
Application data
Organize long-lived engineering documents with transactions, persistence, attributes, and product structures.
- OCAF documents
- Transactions and undo
- Attributes and persistence
- Application structure
Where OCCT fits
Applications that construct, analyze, or exchange 3D models
Use OCCT when the application must do more than display a file: it must construct, analyze, transform, exchange, or persist engineering models.
OCCT
Specialized CADCAM and inspectionEngineering simulationMedical imagingArchitecture and BIMDesign automationDigital twinsTechnical viewers
Why OCCT
Source code, license, documentation, and release history
Review the platform through its license, source code, documentation, release history, and public development record.
Open-source terms
OCCT is distributed under LGPL 2.1 with an additional exception. Review the licence and OCCT exception supplied with your chosen release.
Read the licenseNative C++ control
Integrate at the module or toolkit boundary and keep ownership of the application architecture and user experience.
Technical overviewPublic development
Inspect changes, issues, tests, and release tags in the same repository used to evolve the platform.
Open the repositoryProfessional paths
Add focused support, training, maintenance, or commercial components without replacing the open foundation.
Explore supportDeveloped on GitHub
Source, discussions, and issue tracking in one place
Use GitHub Discussions for technical questions and project ideas. Use GitHub Issues for reproducible defects and focused improvement proposals.
Using OCCT in a product
Need a commercial component or engineering support?
Build directly with OCCT, add a DevTool, or send a bounded technical question with the relevant version and workflow.