Format Guide
OpenCASCADE's native exact-geometry format — precise NURBS topology for FreeCAD and OCC-based tools.
Download Free TrialFree 30-day trial. No credit card required. Windows 10/11.
| Extension | .brep, .brp |
|---|---|
| Full name | Boundary Representation (OpenCASCADE native) |
| Geometry type | Exact solid geometry — NURBS, B-spline, topology |
| Open standard | Yes — OpenCASCADE Technology (OCCT) |
| Supports color | No |
| Supports assemblies | Yes — compound shapes |
| Primary tool | FreeCAD, any OCCT-based application |
BREP (Boundary Representation) in the context of .brep/.brp files refers to OpenCASCADE Technology's (OCCT) native file format for storing exact boundary-representation solid geometry. Boundary representation defines a solid by its bounding surfaces, edges, and vertices, with topological relationships between them. The .brep format stores OCCT's internal geometric representation (NURBS surfaces, B-spline curves, exact topology) in a compact ASCII form. It is used in the open-source CAD ecosystem — particularly FreeCAD, Salome, and any tool built on the OpenCASCADE kernel, which also powers 3D CAD Converter.
FreeCAD uses BREP as an intermediate format for its Part workbench and Shape objects. Exporting to BREP preserves exact geometry for reimport into other OCCT-based tools.
Developers building applications on OpenCASCADE use .brep files to serialize and deserialize solid geometry between processing steps in CAD pipelines and automation scripts.
BREP files are used in FEA preprocessing (Salome, GMSH mesh generation) and computational geometry research because they provide exact topology without tessellation loss.
FreeCAD, Salome, GMSH, and any application built on the OpenCASCADE Technology (OCCT) kernel. 3D CAD Converter reads and writes BREP using OCCT.
Commonly converted to STEP for universal CAD exchange, to STL or 3MF for 3D printing, or to OBJ/glTF for visualization.