Caddis CAD REVIEW

Free online STEP viewer

Open STEP and STP files without sending them away.

Caddis is a local-first viewer for supported STEP and STP Part 21 geometry, including faceted/tessellated and selected analytic BREP surfaces. Assemblies, colors, unsupported surfaces, and broader profiles are not universally covered.

Open the free viewerDownload on the App Store
No account required for local viewing. Files stay on your device unless you opt into Cloud.

What is a STEP file?

STEP (often saved as .step or .stp) is a neutral 3D CAD exchange format used to move product and engineering models between systems.

Caddis on iPhone measuring a 7.7-foot stair run in a DWG floor planMeasure a stair run on site

Field-review workflow

From drawing to clear feedback.

  1. 01Open the Caddis web viewer.
  2. 02Choose a STEP or STP file from your device.
  3. 03Inspect the model and continue your review locally.

Built for practical review

Open supported STEP and STP geometryExplicit errors for unsupported surfacesLocal-first processingOptional cloud projects and controlled sharing

Your drawings stay under your control

Caddis is local-first: opening a supported file for local review does not require uploading it. If you choose Caddis Cloud, you can continue a project across devices or create a revocable, read-only link.

Frequently asked questions

Do I need an account to use Caddis?

No. You can open and review supported files locally without creating an account. An account is only needed for optional cloud features.

Are my CAD files uploaded?

Not for local viewing. Caddis processes supported files on your device. Cloud storage and share links are opt-in per project.

Can I use Caddis offline?

Local review is designed to work on your device. Cloud sync and share links naturally require an internet connection.

Which CAD formats can Caddis open?

Caddis opens supported geometry from DWG, ASCII DXF, STL, OBJ, PLY, STEP/STP, and IFC files. DWG, STEP/STP, and IFC compatibility is limited by source version and geometry type; unsupported geometry is reported rather than silently replaced.

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