Free online BREP converter. Convert Open CASCADE .brep CAD files to STL, GLB, glTF, OBJ, PLY in your browser — processing happens locally, no watermark.
.brep model. The first time you open the page it loads the Open CASCADE (OCCT) kernel compiled to WebAssembly — a one-time download of a few megabytes — then parses the file and shows it in a 3D preview so you can confirm the geometry loaded.A .brep file is the native boundary-representation serialization of Open CASCADE Technology (OCCT), the open-source C++ CAD kernel published under the GNU LGPL. FreeCAD is built on OCCT, which is why FreeCAD users encounter .brep files most often. Unlike a mesh, BREP stores exact geometry: it describes a shape by its boundaries — vertices, edges, wires, faces, shells, and solids — backed by precise curves and NURBS surfaces. It is an ASCII text format specific to the OCCT kernel, not an ISO or vendor-neutral committee standard, so very few applications outside the OCCT ecosystem read it directly.
That is exactly why people convert it. A .brep is great for storing engineering geometry losslessly inside an OCCT-based workflow, but it is a poor file to share: a 3D printer, a game engine, a web viewer, or a colleague using Blender cannot open it. Converting turns that exact CAD geometry into a triangle mesh the rest of the 3D world understands:
.glb bundles the mesh into a single portable file for <model-viewer>, WebXR, Unity, and Three.js.Note this is a one-way conversion into mesh formats. BREP stores exact surfaces and a mesh is an approximation, so there is no faithful "mesh back to BREP" route. A different kind of conversion — BREP to STEP or IGES — stays exact because those are also boundary-representation formats; that lossless CAD-to-CAD hand-off is done inside a CAD program like FreeCAD, not by tessellation.
| Property | Value |
|---|---|
| Full name | Boundary Representation (B-rep) |
| Origin | Open CASCADE Technology (OCCT) kernel — native serialization |
| Encoding | ASCII text |
| Geometry type | Exact surfaces and solids (not a mesh) |
| Stores | Vertices, edges, wires, faces, shells, solids; curves & NURBS surfaces |
| Color / materials | None — geometry only |
| Standardized? | No ISO / vendor-neutral standard; OCCT-specific |
| Common source app | FreeCAD (built on OCCT) |
| Opens natively in | FreeCAD and OCCT-based tools; convert to mesh for everything else |
| Format | Type | Geometry | Materials / color | Best for |
|---|---|---|---|---|
| BREP (.brep) | Exact B-rep (OCCT kernel) | Precise faces, edges, NURBS surfaces | None | Lossless CAD geometry inside OCCT / FreeCAD |
| STL (.stl) | Triangle mesh | Tessellated approximation | None | 3D printing, slicers |
| OBJ (.obj) | Text mesh (+ optional .mtl) | Tessellated approximation | External .mtl + images |
Modeling apps, broad compatibility |
| GLB / glTF | glTF 2.0 (binary / JSON) | Tessellated approximation | Embedded PBR + textures | Web, AR, game engines |
| PLY (.ply) | Polygon mesh | Tessellated approximation | Per-vertex color | Scans, point clouds, research |
| 3MF (.3mf) | Zipped XML print package | Tessellated approximation | Embedded color + units | Modern color 3D printing |
BREP is the native format of the Open CASCADE Technology (OCCT) kernel, so the programs that read and write it directly are OCCT-based — most commonly FreeCAD, which is built on OCCT, along with developer tools that link the OCCT libraries or Python frameworks such as build123d. General 3D apps like Blender, Maya, and slicers cannot open .brep at all. The practical way to view or edit a .brep outside an OCCT program is to convert it to a mesh format such as STL, OBJ, or GLB first.
Yes, by necessity, when the target is a mesh. BREP stores exact geometry — true curves and surfaces — while STL, OBJ, GLB, PLY, and 3MF are all triangle meshes. Converting tessellates the model: curved faces are broken into flat triangles, an approximation rather than an exact copy. A denser tessellation looks smoother and hugs the original surface more closely but produces a larger file; a coarser one is lighter but shows faceting on curves. For most printing and visualization the default tessellation is fine, but anything depending on exact dimensions should stay in a CAD format.
Not with this tool — it outputs mesh formats (STL, OBJ, GLB, glTF, PLY, 3MF) only. A BREP-to-STEP or BREP-to-IGES conversion is a different animal: STEP and IGES are also boundary-representation formats, so that hand-off stays exact and lossless with no tessellation. The straightforward way to do it is in FreeCAD — open the .brep, then use Export and choose STEP (.step) or IGES (.iges). Reach for that route when the destination is another CAD system; reach for this converter when the destination is a printer, viewer, or game engine that needs a mesh.
Both are boundary-representation formats that store exact solids, so geometrically they are close cousins. The difference is ownership and reach: BREP is OCCT's internal, native serialization — fast and faithful inside FreeCAD and other OCCT tools, but read by almost nothing else. STEP (ISO 10303) is the vendor-neutral interchange standard that SolidWorks, Fusion 360, CATIA, Onshape, and FreeCAD all read. Keep your model in BREP for OCCT/FreeCAD work; export to STEP when you need to share editable CAD geometry with someone on different software. If your file is already a STEP model, use our STEP converter to turn it into a mesh instead.
Not with a simple converter. BREP is exact parametric geometry and a mesh (STL, OBJ, and the rest) is a triangle approximation, so there is no faithful "mesh to BREP" route — the exact surfaces were discarded during tessellation and cannot be recovered by re-reading triangles. Turning a mesh back into solid CAD geometry requires reverse-engineering or surface-reconstruction tools inside a CAD package, not a file conversion. This tool converts BREP to mesh formats only.
STL for the widest slicer support, or 3MF if you want color, units, and print metadata to travel with the model. Both discard the exact CAD surfaces and keep just the printable triangle mesh, which is what a slicer needs. If your BREP has curved surfaces, make sure the tessellation is dense enough that round features print smoothly rather than faceted — check the 3D preview before you export.
Because the conversion runs on your own device rather than a server, the real limit is your browser and available memory, not an upload cap. Typical mechanical parts — a few megabytes of .brep — convert quickly. Very large assemblies with millions of faces can get heavy, since the OCCT WebAssembly engine has to hold both the exact geometry and the generated mesh in memory; on such files a desktop FreeCAD export is more comfortable. For the great majority of single-part and small-assembly files, the in-browser converter handles them without trouble.
No. This converter runs entirely in your browser using the Open CASCADE engine compiled to WebAssembly — fittingly, the same kernel that defines the BREP format. Your .brep is parsed, tessellated and exported on your own device. The engine downloads once the first time you use the page and then runs locally, which means no upload wait, no account, and nothing for us to store. In our testing, converting a BREP solid to GLB produced a single self-contained binary mesh with the geometry intact and no material data — exactly what you expect from a geometry-only source, since a plain .brep carries no textures or color to bring along.