An ISO 10303-21 STEP file (AP214 schema) containing a manifold solid B-rep where every mesh triangle becomes a planar face. If the mesh is watertight you get a solid body; if it has holes or non-manifold edges you get a surface body (open shell) instead. Units are written as millimetres — pick the units your STL was modelled in above and we scale correctly.

Every triangle becomes a STEP face, and CAD packages get slow above roughly 50–100k faces (a 1-million-triangle scan would produce a ~750 MB STEP that most CAD software can't open). Dense meshes are simplified with quadric edge-collapse, which keeps the shape within a fraction of a millimetre while cutting the face count. Raise the limit if you need more detail and your CAD can handle it.

No. Parsing, simplification and STEP writing all run inside a Web Worker in your browser. You can disconnect from the internet after the page loads and it still works. Nothing is stored or sent to us unless you submit the quote form.

Binary and ASCII STL are supported. Practical limits depend on your device's memory — a 200 MB binary STL (about 4 million triangles) converts in under a minute on a typical laptop. Very large files may fail on phones or low-memory machines.

Yes — that's a manual reverse-engineering job our 3D scanning team does regularly. Convert your file here, then use the quote form to send us the details.