Open STEP files in your browser
View .stp / .step (AP203, AP214, AP242) and .igs / .iges files — with the assembly tree, colours, units and which CAD system made the file. Nothing is uploaded: the file is opened on your own computer.
Drop a STEP or IGES file here, or click to choose
.stp · .step · .igs · .iges 🔒 Opened locally — nothing leaves your computerFile
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STEP versions: AP203, AP214 and AP242
STEP (ISO 10303) comes in several “application protocols”. The viewer tells you which one your file uses, because it explains most “this file won't open” problems.
| Protocol | What it carries | Typical source |
|---|---|---|
| AP203 | Geometry and assembly structure | Older CAD systems, many downloads |
| AP214 | AP203 plus colours, layers and more metadata | Most CAD exports of the last 15 years |
| AP242 | Replaces both; adds manufacturing information (PMI), tessellated geometry and newer editions | Current SolidWorks, NX, CATIA, Creo, Fusion 360 |
Older viewers only understand AP203/AP214 and reject AP242 files — especially newer editions. This viewer uses OpenCascade, which reads all three. If it still can't open your file, one click sends it to our server-side CAD engine instead.
Have a mesh instead? Turn it into STEP
STL, OBJ and PLY files are triangles, not CAD surfaces. Vertessia can rebuild a mesh or a 3D scan as a STEP made of smooth NURBS surfaces. Mesh to STEP → · Check if an STL is watertight →
FAQ
Is my file uploaded?
No. The viewer runs in your browser using OpenCascade compiled to WebAssembly (about 8 MB, downloaded once the first time you open a file). Only if you choose the server fallback or a conversion is the file uploaded.
Which files can I open?
STEP AP203, AP214 and AP242 (.stp, .step) and IGES (.igs, .iges). Very large assemblies may be slow or run out of browser memory — use the server fallback for those (up to 100 MB).
Why is my model shown in millimetres?
Sizes are shown in millimetres whatever unit the file uses; the file's own unit is listed under File.
Can I convert the STEP to STL, OBJ or 3MF?
Yes — use the convert buttons under the viewer. Converting STEP to a mesh is free, with adjustable triangle size.