Private, in your browser
STEP files are read on your own computer by OpenCascade compiled to WebAssembly. Nothing is uploaded.
STEP Viewer: Open STEP Files Online
Open STEP files from SolidWorks, Fusion, Onshape or FreeCAD without a CAD license. Check parts, size and print readiness. Nothing uploaded.
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Drag to rotate
Open a file to see its size, triangle count and whether it is watertight.
Opened in your browser. Files are never uploaded.
Continue with your STEP file
Convert it for printing, or open a different CAD format.
How to open a STEP file online
Open the file, turn it around, then read the numbers before you print or convert it.
- 1
Open the STEP file
Drop a .step or .stp file, or several to switch between them. The CAD reader loads the first time.
- 2
Rotate and inspect
Drag to orbit and scroll to zoom. Turn the file's own colors on or off, or show the triangle wireframe.
- 3
Check and download
Read size, volume and the watertight result, then save the part as an STL if you want to print it.
Why use this STEP viewer
A quick look at a CAD part without installing a CAD program.
Assemblies and part names
Each solid in an assembly becomes its own object, in place, with the name the CAD program gave it.
Colors from the file
Part and face colors saved in the STEP file show up. Switch them off to see the plain geometry.
Real size
Whatever unit the file was saved in, the size reads in millimeters, or in inches with one click.
Watertight check
Counts open and non-manifold edges in the triangle mesh, so you know whether the part will slice cleanly.
Volume and filament
Solid volume in cubic centimeters and a PLA weight estimate for printing the part solid.
What's inside a STEP file
STEP is the ISO 10303 standard for moving 3D CAD models between programs. Four things set it apart.
Exact surfaces, not triangles
Planes, cylinders and freeform NURBS surfaces are stored as exact math. Any program that shows or prints them turns them into triangles first, and so does this viewer.
Units in the file
Unlike STL, a STEP file says whether its numbers are millimeters, inches or meters, so parts open at their true size.
Assemblies, names and colors
One STEP file can hold a whole assembly: many parts with their positions, names and colors.
Plain text, no history
STEP is a text file (ISO 10303-21). It carries the finished shape but not the feature tree, so sketches and dimensions are not editable after export.
Who opens STEP files
STEP is how CAD files travel between companies, so many people receive one without owning CAD.
Makers using downloaded parts
Supplier catalogs and GrabCAD share motors, rails and fasteners as STEP. Check the size before you design a mount around one.
Buyers, managers and clients
Review a part someone emailed you without a CAD license, on any computer with a browser.
3D printing services
Customers often send STEP instead of STL. Check size and volume for a quote, then convert it for the slicer.
Students and Chromebook users
Open a STEP file from a class or a forum on a Chromebook or tablet, where desktop CAD programs do not run.
STEP viewer questions
Answers about software, privacy, file extensions, accuracy, assemblies and printing.
How do I open a STEP file without CAD software?
Drop it onto this page. The viewer runs in Chrome, Edge, Firefox and Safari on Windows, macOS, Linux and ChromeOS, with nothing to install and no account.
Is my STEP file uploaded?
No. The file is read in your browser by OpenCascade, an open source CAD kernel compiled to WebAssembly. The first CAD file you open downloads the reader once; your model never leaves your device.
What is the difference between a .step and a .stp file?
None. Both extensions hold the same ISO 10303 format, and CAD programs simply pick one or the other. This viewer opens both.
Why does my part look slightly faceted?
Screens draw triangles, so curved faces are split into small flat facets that stay within 0.05 percent of the part's size from the true surface. The STEP file itself stays exact. Sizes are read from the triangles, so a curved part can measure up to 0.05 percent short.
Can it open STEP assemblies?
Yes. Every solid becomes its own object at its place in the assembly, named as in the CAD program, and the Objects count shows how many there are. Part colors show when the file has them.
Can I 3D print a STEP file?
PrusaSlicer, Bambu Studio and OrcaSlicer import STEP directly, while Cura and many other slicers need an STL. Click Download STL here, or use the STEP to STL converter for batches and separate parts.