View STEP / STP Files Online (Free 3D CAD Viewer)

Open a .STEP or .STP file in 3D in your browser. Rotate, pan, zoom and fit. Nothing is uploaded — parsing runs locally.

Your file is processed locally in your browser. Nothing is uploaded to a server.

STEP / STP viewer

Drop a .STEP or .STP file to view it locally.

On a phone, open the file from Files or Downloads. Photos will not work — pick a .step / .stp document. Processing stays on this device.

Client-side STEP viewing

STEP (ISO 10303) stores B-rep solids, not triangles. This viewer loads an Open CASCADE WebAssembly build in your browser, tessellates the file, and renders it with Three.js. The CAD file is not uploaded to ForgeKit.

Orbit with a drag (or one finger on a phone), pan with right-drag or two fingers, and zoom with the scroll wheel or a pinch. Double-click (or double-tap) a face to set the orbit pivot; Fit frames the whole model. Wireframe is a shader flag on the tessellated meshes — it is not a true CAD edge display.

On iPhone and Android the system file picker often hides unknown CAD types. Use Choose file, then pick the .STEP / .STP from Files or Downloads rather than Photos. A sample cube is included so you can confirm the viewer without a CAD export.

Formats now and later

.STEP and .STP work today. The viewer module is isolated so STL, OBJ, DXF and IGES can be added without touching the rest of the platform. Huge assemblies are limited by device memory; export a lighter STEP from your CAD system if the tab struggles.

Estimating bar or plate from a model? Use the material weight calculator with dimensions you read off the part.

Frequently asked questions

Are my CAD files uploaded to a server?+

No. STEP parsing runs in WebAssembly inside your browser. The file never leaves your device. That is why large assemblies are limited by your computer’s memory rather than a network upload.

Which formats work today?+

STEP and STP (AP203/AP214 style files that Open CASCADE can tessellate). The viewer is structured so STL, OBJ, DXF and IGES can be added later without changing the rest of the site.

Why does a large STEP file take time?+

B-rep solids must be tessellated into triangles. Complex assemblies with tight tolerances take longer. Keep the tab in the foreground; a progress state is shown while the WASM engine works.

Can I measure or explode assemblies?+

The viewer is for inspecting the 3D model. For bounding-box size, a clicked dimension and an estimated weight from a material, use the STEP quote tool on AlwaysReach.

Why won’t a STEP file open on my phone?+

Phone photo pickers do not list CAD files. Use Choose file, switch to Files / Downloads, and select a .step or .stp document. If the file has no extension, the viewer still accepts it when the contents start with ISO-10303-21. Very large assemblies can run out of memory on a phone — export a simpler STEP from CAD if that happens.

The model looks off-centre and I cannot re-focus it+

Use Fit to frame the whole part. Double-click (desktop) or double-tap (phone) a face to put the orbit pivot on that point, then drag to rotate around it. Pinch or scroll zooms toward the cursor; two-finger drag or right-drag pans.

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