Open .step and .stp files free in your browser, read by a real CAD kernel and normalised to true millimetres. Measure it, print-check it, export STL or 3MF.
Someone sent you a .step (the format Fusion, SolidWorks and FreeCAD open) and nothing on your machine will open it. Drop it here: the same geometry engine CAD tools use reads it in your browser, in true millimetres, so the dimensions you measure are the dimensions the part was drawn to. Then measure it, check it prints, and take it further.
Free to use · Runs in your browser · Start without an account
STEP is the format mechanical CAD speaks. Most quick previews render it and stop; the useful questions all come after that.
OwlCAD reads .step and .stp with OCCT, the same open geometry engine desktop CAD tools use, running locally in your browser. Your file is read on your device, not queued behind someone else’s upload.
This is where STEP beats STL outright: a STEP file records its own units and OwlCAD normalises them to millimetres on read. There is no interpretation bar and no 25.4× surprise: the part opens at the size it was designed.
Edge lengths, hole radii and diameters, true arc lengths, face areas, angles, and the smallest gap between two parts, plus overall size, volume and triangle count. The numbers you need to make something fit a part you did not draw.
Run the print check for thin walls, overhangs (areas that would need supports), watertightness (closed, with no holes, so a slicer reads it as solid), and fit against your printer’s build volume, auto-orient it on the plate, and see what it will weigh and cost in filament before you slice.
Combine and cut the imported part with parametric shapes (union, subtract, intersect): add a mounting boss, cut a clearance hole, hollow it, or build an adapter around it. Non-destructive and fully undoable, like everything else here.
Export print-ready STL or 3MF for Bambu Studio, PrusaSlicer, Cura or OrcaSlicer at true millimetre scale, or OBJ and GLB for other 3D tools, plus SVG or DXF of a 2D projection for a laser cutter or CNC.
You do not need desktop CAD software to look at a .step or .stp file. It opens here, in a browser tab, with nothing to install.
Drag the .step or .stp onto this page or onto the editor’s build plate, or click to choose it. A real CAD engine reads it in your browser and normalises its units to millimetres, so it arrives at the size it was designed.
Orbit around the part, then measure edge lengths, hole diameters, arc lengths and the gap between two parts. Run the print check to see thin walls, overhangs, and whether it fits your printer’s build volume.
Export STL or 3MF for your slicer at true millimetre scale, or OBJ and GLB for other 3D tools.
It opens on your device, it is saved to your workspace as you work, and it exports back out in the format your slicer wants.
Your browser reads and renders the model itself, so it appears as soon as you drop it in — you are never queued behind anyone else’s upload, and the file does not travel anywhere before you can see it.
Most online viewers forget your file the moment you close the tab. OwlCAD keeps the model in your own workspace and syncs it as you work, so it is still there when you come back to this browser. Create a free account and it follows you to any device, and your projects dashboard lets you delete anything you no longer want.
When you are done, export STL, 3MF, OBJ, GLB or STEP — the format your slicer or your colleague actually needs, not a project file that only opens here.
No download, no account needed. It opens in your browser at true size.
Yes. Drop a .step or .stp onto the build plate and OwlCAD reads it with OCCT, the open geometry engine (CAD kernel) desktop CAD tools use, running in your browser. Nothing installs, and no account is needed to start.
Yes, and this is where STEP beats STL outright. A STEP file records its own units, and OwlCAD normalises them to millimetres on read — so there is no unit guess and no 25.4× surprise. The dimensions you measure are the dimensions the part was designed to.
Yes. Measure its edges, hole radii, arc lengths, face areas, and the gap between two parts; read overall size, volume, and triangle count; run the print check for thin walls, overhangs, and build-volume fit; and cut, combine, hollow, or scale it against parametric shapes before exporting a print-ready STL or 3MF.
Not as a feature tree. OwlCAD reads the B-rep and tessellates each part into a mesh, keeping an assembly’s parts, names and colours, so you get accurate, correctly-scaled bodies you can measure, cut, and print — but not the original sketches and features to re-drive. Parts you build in OwlCAD itself stay fully parametric, and those export back to STEP as true analytic B-rep.
Yes. Open the .step and export STL, 3MF, OBJ, or GLB, at true millimetre scale and ready for any slicer. Going the other way, an imported mesh exports to STEP as a faceted shell rather than editable analytic surfaces, so OwlCAD is not a mesh-to-CAD converter and does not claim to be.
Yes. Opening, inspecting, measuring, editing, and exporting are free forever, with no watermark. Only AI generation is part of OwlCAD Pro.