BREP File

What are BREP files and how to open them

Are you having problems opening a BREP file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your BREP files.

What is a BREP file?

A .BREP file is an Open Cascade Technology 3D Model file.

Open Cascade Technology 3D Model files store precise 3D shape data using a boundary representation format designed by the Open CASCADE Technology (OCCT) library. They are used to preserve exact geometric and topological information - not meshes - for solids and surfaces built from vertices, edges, faces, shells, and more.

These files are generated and read by OCCT itself, particularly using the BRepTools (for ASCII) or BinTools (for binary) modules. The format supports combining individual shape elements into complexes such as compounds and composites, with full information about transformations, orientations, and nested spatial location.

All geometry types typically found in CAD are supported - including analytic 3D curves (lines, circles, ellipses, hyperbolas, parabolas, Bézier, B-spline, and offset curves), analytic surfaces (planes, cylinders, cones, spheres, tori, extrusions, revolutions, offsets, Bézier, and B-spline surfaces), 2D curves for trimming, polygons, triangulations, and polygons on triangulations.

The standard version of the format is plain-text (ASCII), with the file laid out in sections: a signature ("DBRep_DrawableShape"), version line (for example "CASCADE Topology V1..."), followed by sections for locations (transformations), geometry (curves, surfaces, triangulations), and shapes (vertices, edges, faces, solids). OCCT also provides a binary variant via its BinTools package, which stores similar content in a compact form.

Internally, files often begin with the ASCII signature DBRep_DrawableShape at offset zero. Other identifiable keywords include "POLYGONONTRIANGULATIONS", "CASCADE TOPOLOGY V1", "MATRA-DATAVISION", "LOCATIONS", "POLYGON3D", "CURVE2DS", "SURFACES", "TSHAPES", and "CURVES".

How to open BREP files

Important: Different programs may use files with the BREP file extension for different purposes, so unless you are sure which format your BREP file is, you may need to try a few different programs.

While we have not verified the app ourselves yet, our users have suggested a single BREP opener which you will find listed below.

Last updated: August 24, 2026

Various apps that use files with this extension

These apps are known to open certain types of BREP files. Remember, different programs may use BREP files for different purposes, so you may need to try out a few of them to be able to open your specific file.

Help us help others

File.org helps thousands of users every day, and we would love to hear from you if you have additional information about BREP file formats, example files, or compatible programs. Please use the links below or email us at submit@file.org to discuss further.