STEP file viewer

1. Drop your .step or .stp file above (or choose it from your device).
2. The file is read by OpenCascade, the same open-source CAD kernel PrusaSlicer, Bambu Studio and OrcaSlicer use, running right in your browser.
3. Spin, zoom and pan the model. Assemblies show as a part list grouped by sub-assembly. Untick parts to hide them.
4. Click Measure and pick two points to get the distance in mm. Points snap to corners.
5. Download as STL, 3MF (keeps parts and colours) or OBJ, or the visible parts only.

Your file is never uploaded. That matters for client and supplier CAD files, which are often confidential.

STEP is the standard way CAD programs swap 3D models. It's defined in ISO 10303, and a .step or .stp file is the plain-text form of it. The two extensions are the same format.

Unlike STL, a STEP file stores exact geometry: real cylinders, arcs and flat faces (a “boundary representation”), plus the assembly tree, part names and often colours. That's why engineers send STEP: it opens in any CAD program and nothing is approximated.

You'll see three versions (“application protocols”) in file headers:

• AP203: the original geometry and assembly protocol from 1994.
• AP214: from the automotive industry; adds colours and layers.
• AP242: the current standard that merges both and adds manufacturing data such as tolerances.

All three open here.

Yes, but a slicer needs triangles, so the file is converted to a mesh first. You have two options:

• Open it in your slicer. PrusaSlicer (2.5 and newer), Bambu Studio and OrcaSlicer import STEP directly and convert it on the way in; Bambu Studio and OrcaSlicer let you set the conversion quality. The free version of UltiMaker Cura doesn't open STEP.
• Convert it here with the STEP to STL converter, then print the STL or 3MF in any slicer. This is handy when you want to check sizes first, print only some parts of an assembly, or use Cura.

To show or print a STEP model, its curved surfaces have to be turned into triangles. This is called tessellation. Two limits control it: how far a triangle may sit from the true surface (the chord tolerance), and how sharp the angle between neighbouring triangles may get. Smaller limits mean smoother curves, more triangles and bigger files.

Deviation scales with the size of the model. Going finer than your printer can reproduce mostly just makes the file bigger, so Normal is the right choice for almost every FDM print.

Print quality doesn't depend on the format as long as the mesh is fine enough. Keep the STEP as your master copy: converting to STL is one-way.