Private browser-based CAD inspector
Free Online STEP Viewer
Open a .step or .stp CAD model directly in your browser. OpenCascade triangulates the precise CAD surfaces locally so you can rotate, zoom and inspect the part without uploading it.
- ✓ No upload
- ✓ STEP + STP
- ✓ CAD assemblies
- ✓ 12 MB safety cap
What this STEP viewer checks
STEP stores boundary-representation CAD geometry rather than only display triangles. The local OpenCascade parser tessellates solids and surfaces into a preview mesh, while preserving separate colored parts when the source exposes them.
- 01 Choose or drop a .step or .stp file.
- 02 Wait while the local CAD engine triangulates its surfaces.
- 03 Rotate, zoom and check mesh and triangle counts.
STEP compatibility
| Feature | Status | What to expect |
|---|---|---|
| .step and .stp | Supported | Both common STEP filename extensions |
| Solid and surface geometry | Supported | Triangulated locally for WebGL display |
| Multi-part files | Supported | Imported mesh parts remain separate |
| Part colors | Best effort | Shown when the STEP reader exposes a color |
| Feature history / sketches | Not shown | Use a full CAD application for editing |
| PMI and dimensions | Not shown | Manufacturing annotations are outside this viewer |
Private local processing
The browser reads the selected bytes and sends them straight to the local parser and 3D renderer. There is no model upload endpoint, account, storage bucket or server-side processing step.
Limits to know
This viewer is an inspection preview, not a CAD editor. It does not expose sketches, feature history, PMI, constraints or editable B-Rep faces. Files are capped at 12 MB, CAD entity counts are checked before parsing, and parsing stops after 60 seconds to protect browser memory.
STEP parsing uses OpenCascade via occt-import-js. View the bundled open-source notice and source links .
Convert or inspect another format
Frequently asked questions
Can I view a STEP file online without uploading it?
Yes. The STEP bytes, OpenCascade parser and WebGL preview all run on your device. TripoSR.ai does not receive or store the model.
Does this viewer support both STEP and STP files?
Yes. .step and .stp are filename extensions for the same ISO 10303 exchange family and use the same local parser here.
Why does loading STEP take longer than OBJ or STL?
STEP contains precise CAD surfaces. The browser must initialize a CAD engine and triangulate those surfaces before WebGL can display them; mesh formats already contain triangles.
Can I convert the opened STEP file to STL?
Yes. Use the linked STEP to STL converter. It reuses the same private browser parser and exports a binary STL suitable for slicers and mesh tools.
What happens to CAD feature history?
Feature history, sketches and constraints are not rendered or exported. The viewer creates a triangle preview from the final visible CAD shape.