Free online STP to GLTF converter

What the STP format is

STP, also called STEP, is a neutral CAD exchange format standardized as ISO 10303. It stores precise boundary-representation geometry such as surfaces, solids, assemblies, product metadata, colors, and sometimes material information.

Mechanical CAD programs including SolidWorks, CATIA, Siemens NX, Autodesk Inventor, Fusion, Creo, and FreeCAD create or import STEP files. You encounter them when exchanging engineering models between CAD systems, downloading manufacturer components, or receiving production and inspection data.

What the GLTF format is

glTF is a real-time 3D delivery format designed for browsers, game engines, AR/VR software, and lightweight model viewers. A .gltf file normally references one or more binary geometry files and textures; a .glb file packages the scene, mesh data, and textures into one binary file.

Unlike STEP, glTF stores polygon meshes rather than exact CAD surfaces and solids. It supports scene hierarchies, transforms, cameras, materials, textures, vertex normals, and animation. Use it when the destination application needs fast rendering instead of editable engineering geometry.

How to actually convert STP to GLTF

Using the built-in online converter

1. Open the STP-to-GLTF converter on 101convert.com.
2. Upload the .stp or .step file and select GLTF as the output format.
3. Start the conversion and download the resulting .gltf file. If the destination supports a single packaged file, choose GLB when that option is available.
4. Keep the downloaded .bin file and texture files beside the .gltf file; the JSON file may reference them by relative filename.

Using desktop CAD software

CAD Exchanger can import STEP and export glTF or GLB while retaining assemblies and model colors more reliably than a basic mesh-only workflow.

1. Open the file with File → Open and select the STP/STEP model.
2. Inspect the assembly tree and hide components that should not be exported.
3. Use File → Export, choose glTF or GLB, and set the tessellation or mesh-quality option.
4. Use a finer tessellation for curved mechanical parts and a coarser setting for large assemblies where file size and loading speed matter more.
5. Open the result in a glTF viewer or the target application and check scale, orientation, colors, and missing texture references.

For additional editing, import the exported mesh into Blender. Blender can adjust materials, object names, transforms, decimation, and export settings, but it does not natively open STEP files; the CAD-to-mesh conversion must happen first.

Quality, compatibility, and limitations

STEP geometry is mathematically precise, while glTF requires tessellation into triangles. Low tessellation can produce visibly faceted cylinders, fillets, and conical surfaces; high tessellation increases polygon count, memory use, and loading time. Use chordal-deviation and angular-deflection controls when the converter provides them.

Assembly structure may be preserved as glTF nodes, but CAD constraints, parametric features, sketches, tolerances, manufacturing metadata, and editable history are not carried over. Convert a STEP file again from the original CAD source if engineering edits are required.

Check the unit setting because glTF uses meters by convention, while STEP files commonly represent millimeters. A unit mismatch can make the exported model 1,000 times too large or too small. Also verify the up-axis and coordinate origin, since CAD systems and real-time applications commonly use different axis conventions.

Prefer .glb for a single distributable file. Use .gltf when separate JSON, binary, and texture assets are useful for inspection or web deployment. Preserve external texture files and relative paths when using the multi-file format.