What is a STEP / STP file?

STEP (ISO 10303) is the workhorse of mechanical CAD interchange — parametric BREP geometry across every major suite. The format stores exact surfaces (cylinders, NURBS, etc.), which are tessellated into triangle meshes for display.

Will the original parametric geometry be preserved?

The browser displays a triangulated approximation. The underlying STEP file isn't modified — drop it back into your CAD package to keep working on the parametric model.

Why does loading take a moment?

On first open we fetch the ~5 MB OpenCascade WebAssembly binary and tessellate every face. Subsequent files in the same session reuse the cached WASM and load far faster.

No. Files are opened entirely in your browser using local JavaScript and WebAssembly. Nothing is sent to a server.

Does it work on mobile?

Yes. The viewer is mobile-first and works on phones, tablets, and desktops.

CAD & PCB.step · .stp

STEP / STP viewer

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STEP / STP · .step · .stp

Open STEP / STP files

ISO 10303 CAD interchange (parametric solids).

Choose a fileor paste · ⌘V

About STEP / STP

ISO 10303 CAD interchange (parametric solids).

STEP (ISO 10303) is the universal exchange format for mechanical CAD — every serious package can write it. We tessellate the parametric BREP geometry locally via OpenCascade compiled to WebAssembly, then render the resulting meshes with three.js. Orbit, frame, toggle the assembly tree, and overlay edges to inspect solids without uploading the file anywhere.

FAQ

What is a STEP / STP file?: STEP (ISO 10303) is the workhorse of mechanical CAD interchange — parametric BREP geometry across every major suite. The format stores exact surfaces (cylinders, NURBS, etc.), which are tessellated into triangle meshes for display.
Will the original parametric geometry be preserved?: The browser displays a triangulated approximation. The underlying STEP file isn't modified — drop it back into your CAD package to keep working on the parametric model.
Why does loading take a moment?: On first open we fetch the ~5 MB OpenCascade WebAssembly binary and tessellate every face. Subsequent files in the same session reuse the cached WASM and load far faster.
Is my file uploaded?: No. Files are opened entirely in your browser using local JavaScript and WebAssembly. Nothing is sent to a server.
Does it work on mobile?: Yes. The viewer is mobile-first and works on phones, tablets, and desktops.

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