Online STEP Viewer

What is a STEP file?

STEP (ISO 10303, files ending in .step or .stp) is the neutral format almost every CAD program can read and write. Suppliers send STEP models because the receiver does not need the same CAD: SOLIDWORKS, Fusion, Onshape, FreeCAD, Inventor, Creo, CATIA and NX all export it. A STEP file holds exact solid geometry (not a triangle mesh like STL) and, for assemblies, the product structure: which parts there are, what they are called and where each copy sits.

What the viewer shows

The model in 3D: left drag to rotate, right drag to pan, wheel to zoom, the cube in the corner for standard views.
The assembly tree with part names and quantities. Click a row to highlight those parts, click the box in front of it to hide or show them.
Display styles: shaded with edges, shaded, hidden lines, wireframe.
Exploded view and section: pull the parts apart along the way they fit, or cut through the model.
Properties: number of parts and kinds, and the overall size in millimetres.

Supported files and sizes

STEP AP203, AP214 and AP242, as .step or .stp. Assemblies and single parts both open; a single solid is shown with a moving section. Files of a few megabytes open in seconds. Large machines work too: in our tests a 66 MB machine with 6,438 placed parts opened in under a minute on an ordinary laptop. Above about 150 MB the browser may run out of memory, and splitting the model into sub-assemblies helps. STL, OBJ and IGES are not supported here.

Private by design

The STEP reader is OpenCascade compiled to WebAssembly and runs in your browser tab. The file is not sent to us or anyone else, so confidential designs can be checked without an upload. A copy stays in your browser's own storage so the workbench can reuse it; clearing the site data removes it. See how the file stays in your browser.

From viewing to a manual

Once the model is open, one click takes the same file to the assembly manual workbench: an AI orders the parts into steps, and you export a model-kit style PDF with exploded drawings and an assembly animation. The first AI plan each day is free.

Questions

Is this STEP viewer really free?

Yes. Viewing needs no account and has no limit on the number of files.

Do I need to install anything?

No. Any recent Chrome, Edge, Firefox or Safari with WebGL works, on Windows, macOS or Linux.

Why does a big file take a while?

The exact CAD surfaces are turned into triangles in your browser. That takes seconds for small parts and up to a minute for machines with thousands of parts; the same file opens faster the next time.

Can I measure distances?

Not yet. The properties panel shows the overall size.

1 free AI plan a day · your STEP file stays in your browser

Open the workbench