1. Enable conversion in your Project
Create or open a Project with a free account. The project owner opens the actions menu and enables Auto-convert STEP to STL. The setting is off by default and available on Free and Pro. Other members cannot change the setting, but their upload permissions still determine whether they can use it.
This is a Project upload option. The standalone Free Diff Tool accepts STL, OBJ and 3MF, not direct STEP input.
2. Upload the STEP as the main model
Choose a self-contained STEP or STP as the primary model in Upload Revision or Submit for Review. Conversion runs in a browser worker before upload. Keep the page open until the upload finishes. The generated STL and original STEP are saved together; editor, license and any extra originals stay with the package.
Merely attaching a STEP to an existing mesh does not convert it. To convert an older attachment, download it and select it as the main model of a new upload. Disabling the setting later does not change historical files.
3. Download the STL for your slicer
Open the saved revision in Versions. Download model gets its preview mesh; Original files also provides Download STL for a converted revision. Download the STEP separately when you need an editable starting point for the next change.
The converter writes coordinates in millimetres. STL itself has no unit declaration, so check the size in your slicer. CAD surfaces become triangles: inspect fine details, walls, orientation and supports before printing. Conversion does not repair shells, union overlapping assembly parts or certify printability.
Limits and supported files
STEP input is limited to 10 MiB, 256 imported meshes and one million output triangles, with a 60-second conversion limit. The whole revision package remains limited to 100 MiB and counts toward the owner's storage and revision allowances.
Complex files may exhaust device memory before reaching those limits. Try a smaller export or a desktop browser if conversion fails. All imported bodies are included in their occurrence coordinates; choose the bodies in your CAD export first. External dependencies are not fetched.
SHAPR, FreeCAD, OpenSCAD, Blender and ZIP files can be retained as original attachments, but are not automatically converted. STEP conversion is available today; conversion of those other native formats is not promised.