STEP File Viewer

How to use

This tool opens STEP and IGES files from CAD programs and shows them in 3D in your browser, with their assembly tree, without uploading them.

1. Add a file: drop it on the box or choose it. It opens STEP (.step, .stp), IGES (.iges, .igs) and BREP files.
2. The first time, the CAD reader loads. It's about 2 MB, so on a slow connection it takes a moment, and a bar shows how far along it is. It stays loaded for the next file.
3. Drag to turn the model, scroll or pinch to zoom, and right-drag or use two fingers to move it. Angled, Front, Top and Side look from a standard direction, and the buttons in the corner of the view bring the whole model back into view and make it Full screen.
4. Parts lists the assemblies and parts with the names and colours the file gives them. Untick a part, or a whole assembly, to hide it. Show all brings everything back. Click a part in the view to pick it out and see its size.
5. Measure gives the distance between two points you click, and Cut open cuts across the model to show inside it.
6. Detail of curves sets how finely curved surfaces are drawn. Fine is smoother, but slower on big assemblies.
7. Save picture downloads the view as a PNG.

The details give the size in the unit the file was made in, and in millimetres when that's different, with the number of parts and triangles.

Frequently asked questions

What is a STEP file?

STEP (.step or .stp) is the common format for passing 3D CAD models between programs such as SolidWorks, Fusion, Inventor, CATIA, Creo and FreeCAD. It describes exact shapes, curves included, and often a whole assembly of named parts. IGES (.iges or .igs) is an older format for the same job.

Are my CAD files uploaded?

No. The file is read and drawn in your browser, and it never leaves your device. The CAD reader itself is downloaded from this site the first time you need it, like the rest of the page.

Why do curved surfaces look faceted?

Screens draw triangles, so curved surfaces are cut into them. Choose Fine under Detail of curves for smoother curves. The file itself keeps its exact shapes; only the picture is approximate.