Free online FCSTD to STP converter

A receiving CAD, CAM, manufacturing, or inspection system may not open FreeCAD’s native .FCStd files. Exporting the model as .STP or .STEP provides a neutral CAD file for exchange and downstream editing.

What the FCSTD format is

.FCStd is FreeCAD’s native document format, used by FreeCAD users for parametric parts, assemblies, sketches, constraints, spreadsheets, bodies, and feature histories. The document can retain editable sketches, dependencies, expressions, placements, and FreeCAD-specific metadata.

FCStd is intended for continued editing in FreeCAD. Other CAD applications generally cannot read its complete parametric history, even when they can import some of its geometry through another route.

What the STP format is

.STP and .STEP are filename extensions for ISO 10303 STEP exchange files. STEP normally stores precise boundary-representation solid and surface geometry rather than a polygon mesh. Depending on the export protocol and receiving software, it can also carry assembly structure, object names, colors, layers, and other product information.

STEP is supported by many mechanical CAD, CAM, manufacturing, engineering, and inspection systems, including applications such as SolidWorks, CATIA, Siemens NX, and Fusion. It is usually more suitable than STL when the recipient needs accurate faces, edges, curves, or solid geometry instead of a triangulated surface.

How to convert FCSTD to STP

Using FreeCAD desktop:

1. Open the .FCStd document in FreeCAD and recompute it. Resolve failed features, broken links, and Boolean errors before exporting.
2. In the Model tree, select the final Body, solid, surface, or top-level assembly objects that should be transferred. Select final results rather than both a feature and its earlier source features; selecting both can create duplicate geometry.
3. Choose File → Export.
4. Choose a STEP file type in the export dialog and save the result with a name such as part.step or part.stp. The extension does not change the underlying STEP format.
5. Reopen the exported file in a new FreeCAD document or the target CAD application. Check the number of bodies, solid validity, placement, units, faces, and assembly relationships.

For repeated conversions, FreeCAD’s Python console can export explicitly selected shape-bearing objects:

import FreeCAD as App
import Part

doc = App.openDocument("model.FCStd")
doc.recompute()
objects = [doc.getObject("Body")]
Part.export(objects, "model.step")

Replace Body with the names of the final objects to export. Do not use a script that blindly exports every visible object when the document contains construction geometry, intermediate features, or overlapping results.

Users can also convert the file for free on 101convert.com without installing software. The online method is appropriate only when uploading the design is acceptable and the service supports the file size and geometry involved.

Quality and compatibility limits

The conversion transfers the model’s resulting geometry, not its original FreeCAD feature tree. Sketch constraints, expressions, spreadsheets, design history, and many FreeCAD-specific objects are not recoverable from the STEP file. The recipient normally receives imported solids or surfaces that can be measured and sometimes edited, but cannot be regenerated through the original FreeCAD operations.

STEP export may preserve assembly and appearance information through AP214 or AP242 workflows, but the available settings and retained data depend on the FreeCAD version, export options, and receiving application. Some importers flatten assemblies or ignore colors, names, layers, and metadata.

A document containing only a mesh, non-manifold geometry, missing faces, or unresolved Boolean failures will not become a valid STEP solid merely by changing .FCStd to .STP. Repair the geometry, convert suitable mesh data into valid CAD geometry, or remodel the affected part before exporting.