STEP & IGES Viewer for macOS

STEP Viewer opens STEP and IGES CAD files on your Mac, the way the rest of this suite handles their formats: a proper 3D view you can orbit, plus Quick Look previews and real Finder thumbnails, so you can see what a part is without opening anything.

It reads the exact B-rep geometry with the OpenCASCADE kernel and tessellates it on your Mac. Assemblies keep their authored per-part colours, so the pieces stay distinct. Nothing is uploaded, and it works fully offline.

Formats

STEP (.step, .stp), including AP203, AP214 and AP242
IGES (.iges, .igs)

Both are exact CAD interchange formats, carrying trimmed surfaces and topology rather than a mesh, so the app tessellates them for display with a full CAD kernel running on your machine.

Prefer the browser?

No install needed: the STEP and IGES Viewer opens the same files right in your browser, with nothing uploaded.

Requirements

Universal binary, so it runs on both Intel and Apple Silicon Macs.

macOS 14 (Sonoma) or later
Intel Mac or Apple Silicon (M1 or newer)

Installation

Download the file, unzip it, and copy it into your Applications folder. Open it once and it registers the Quick Look handler itself, so previews and thumbnails start working in the Finder. Instructions are included with the download.

The app is signed and notarised by Apple, so you should not see any Gatekeeper warnings.

Licence

The STEP Viewer application. You may install and use it, at no cost, on any Mac you own or control, for personal or business purposes. You may not sell, rent, lease or sublicense it, or charge anyone for it, and you may not repackage or host it for download (please point people at this page instead). The software is licensed, not sold, and all rights not granted here are reserved by the copyright holder.

The CAD engine. STEP Viewer reads CAD files using OpenCASCADE Technology, which is licensed under the GNU Lesser General Public License, version 2.1 (LGPL-2.1). That component is separate from the terms above: it is bundled as a replaceable library, and you may modify or replace it as the LGPL permits. The full licence, and the complete corresponding source for the exact version used, ship with the app and are linked from its About box.

Privacy

100% on-device. No accounts, no tracking, never connects to the internet, collects no data whatsoever.