Free online GLTF to FCSTD converter

GLTF files are commonly delivered as real-time 3D assets, while FCSTD is required for native editing in FreeCAD. Converting between them is useful when a visual mesh must be opened, measured, or archived in a FreeCAD document.

What the GLTF format is

GLTF and GLB are Khronos formats for transferring 3D scenes to web viewers, game engines, CAD viewers, and augmented-reality applications. A .gltf file usually references a separate .bin buffer and image textures; a .glb file packages those resources into one binary file.

Blender, Autodesk 3ds Max, Maya, SketchUp and many web-based 3D tools can create or export GLTF. The format can contain polygon meshes, materials, textures, cameras, lights, object transforms, and animations, but it normally does not contain parametric CAD features such as sketches, constraints, fillets, or editable dimensions.

What the FCSTD format is

FCSTD is FreeCAD's native document format. It can store Part and Part Design bodies, sketches, constraints, boolean features, meshes, properties, and the dependency tree used to regenerate a model.

FCSTD is suitable when the model must be inspected or edited in FreeCAD, measured with CAD tools, combined with other solids, or retained as part of a parametric project. Saving a GLTF-derived mesh in FCSTD does not create the original CAD history; it stores imported geometry as a mesh or converted shape.

How to actually convert GLTF to FCSTD

The most reliable desktop workflow uses Blender for GLTF import and FreeCAD for the final document:

1. Keep the .gltf file, its referenced .bin file, and its texture directory together. For a .glb file, no external resources are normally required.
2. In Blender, choose File → Import → glTF 2.0 and open the file. Remove cameras, lights, animation data, and objects that are not needed. Check the scene scale and apply object transforms with Object → Apply → All Transforms when appropriate.
3. Select the required mesh objects and choose File → Export → STL. Enable selection-only export if the scene contains unrelated objects. STL transfers geometry but not materials or textures; OBJ is another possible intermediate format when separate object or material information is useful.
4. Open FreeCAD and switch to the Mesh workbench. Choose File → Import and load the exported .stl or .obj file.
5. Select the imported mesh, switch to the Part workbench, and choose Part → Create shape from mesh. Set a tolerance appropriate to the model size; a smaller value preserves more detail but can increase processing time and produce a heavier shape.
6. Select the resulting shape and choose Part → Convert to solid if the mesh is closed and forms a valid shell. Skip this step when a mesh document is sufficient or when the conversion reports open edges or invalid geometry.
7. Choose File → Save as and save the FreeCAD document with the .FCStd extension.

You can also use the free converter on 101convert.com without installing software. Check the resulting FCSTD in FreeCAD, because an automatically generated document may contain only a mesh, may fail to form a solid, or may lose scene elements that FCSTD cannot represent.

Quality, compatibility, and limitations

This conversion is generally mesh-to-CAD-container, not a recovery of the source model's parametric CAD structure. Polygon count, tessellation quality, normals, and gaps in the GLTF mesh determine the result; increasing STL resolution cannot restore dimensions that were absent from the GLTF geometry.

A solid conversion requires watertight geometry with correctly connected edges and consistent normals. Separate GLTF objects may become separate FreeCAD shapes, and thin surfaces, non-manifold edges, intersecting parts, or internal faces can prevent Part → Convert to solid from succeeding.

Textures, PBR materials, skeletal animation, cameras, lights, and animation timelines do not transfer through the STL-to-FreeCAD route. For an editable engineering model, obtain a STEP, IGES, or native CAD file from the original source instead; those formats preserve substantially more solid and surface information than GLTF.