# CAD Assistant

> Offline 3D CAD and mesh model viewer and converter. (iPhone/iPad app by OPEN CASCADE.)

- Source: https://appshunter.io/ios/app/cad-assistant/id984561628 (this page in markdown: same URL + `.md`)
- Developer: [OPEN CASCADE](https://appshunter.io/developer/984561627)
- Category: Productivity
- Price: Free
- Rating: 4.70/5 from 15 App Store ratings · 9 written reviews indexed
- Age rating: 4+
- Requires: iOS 8.0 · 63 MB
- Released: 2015-06-14
- Data updated: 2026-07-25
- Monetization: free
- User reviews in markdown: https://appshunter.io/ios/app/cad-assistant/id984561628/reviews.md

## What is CAD Assistant?

OPEN CASCADE CAD Assistant for iOS is an offline viewer and converter for 3D CAD and mesh models.

If you wish to use this technology for development of customized solutions for your business, contact us at:
https://www.opencascade.com/contact

Basic CAD model viewing and converting

Basic functionality is provided by CAD Data Exchange component of Open CASCADE Technology (OCCT).
The supported file formats and data are:
- BREP: native OCCT format for shape geometry, topology, and assembly structure.
- IGES (5.1 and 5.3): shape geometry, colors, top-level object names, file information.
- STEP (AP203 and AP214): shape geometry, assembly structure, colors, names, validation properties, file information.

Assembly structure of the model can be navigated through the tree browser. The components of the assembly can be hidden or shown as necessary to inspect the model. The selected sub-assembly or part can be queried for its properties.

CAD model (whole or selected part or sub-assembly) can be exported to any of supported CAD or mesh formats.

Viewing mesh data

Additional functionality is viewing of mesh models with associated data, implemented using the mesh visualization component of OCCT.

Supported mesh formats are:
- STL is de-facto standard in 3D printing.
- PLY has capability to store data associated with mesh nodes and elements. If you have in your application a model represented by mesh, it can be saved easily to PLY format and viewed on a tablet. Additional data (RGB color or scalar) can be added to each polygon or node.
- OBJ is standard for 3D animation and supported by most 3D graphics applications.
- JT is ISO standard for efficient visualization of 3D CAD data.
- glTF is an open standard for 3D assets.

CAD Assistant allows you to view the mesh in wireframe, shaded, and shrink view. If mesh contains associated textures, colors, or scalar data, it can be viewed with elements colored according to the selected property. For scalar quantities interactive color scale is shown, providing controls to manipulate the range of displayed quantities.

Common operations

CAD Assistant is optimized for devices with multi-touch screen and provides intuitive manipulation of the 3D view by finger gestures.

Left toolbar provides buttons for fitting model to window and choice of standard views. Settings submenu provides access to viewer and application options, file information, and message log.

Files can be opened from local storage of the application (uploaded using iTunes). In addition, models can be opened from other applications, like attachments within mail client.

CAD models can be saved in STEP, IGES, or BREP format as CAD data; CAD and mesh models can be saved in PLY, STL, OBJ or glTF format as polygonal data. Save file dialog also allows saving current image of the model to PNG format. If target directory Mail is selected, the mail client will be automatically started with saved file as attachment.

Known limitations

Depending on a device, opening large files may take time, or will be disallowed at all due to device memory limits. In general, files less than 50 Mb can be considered safe for opening on all devices.

See more at https://www.opencascade.com/content/3d-applications

Feedback

We welcome your feedback on our User Forum at https://www.opencascade.com/forums/applications

## Key features

- Offline viewing and conversion
- Supports BREP, IGES, STEP, STL, PLY, OBJ, JT, glTF formats
- Assembly structure navigation
- Model property inspection
- Export to CAD and mesh formats
- Mesh visualization with wireframe, shaded, and shrink views
- Intuitive multi-touch gestures

## Recent user reviews (9 of 9)

All indexed reviews: https://appshunter.io/ios/app/cad-assistant/id984561628/reviews.md

### 5/5 — Best free 3D file viewer on the App Store

*2026-04-09, version 1.2*

Simple interface. Easy to open 3D models from cloud storage sources into this App. I am mostly using it to view STEP files so I can’t comment on the other formats.
Thank you for taking the time to port your awesome 3D viewer tech to iOS!!!
I am amazed there aren’t more 5 stars reviews. So I am taking the time to write one, which is rare. 
And I will tell every engineer I run into to check it out. 
Keep up the good work guys!

### 4/5 — Really good!

*2026-03-20, version 1.2*

Lots of CAD formats are supported. Perfect viewer app to quickly check / show 3D objects when on the go. Thank you OpenCascade!!

### 2/5 — Cannot access files on iPad

*2025-12-14, version 1.2*

Seems like a great app but I cannot seem to,access any local files on my iPad. I’m running the latest iOS.

### 1/5 — Very week

*2024-06-01*

This app is so bad.  You cant even important a step file , really very useless

### 5/5 — No login needed. Works well.

*2023-08-07, version 1.2*

This may be the only free viewer on the entire App Store that opens step files from any source and doesn't require a log in.

### 4/5 — Looks good

*2023-02-02, version 1.2*

Works well. It can be hard to open certain files (like OBJ) as you can’t directly send them to the app. Need to use apple files and hope the app folder exists.

### 1/5 — I don’t know how to use it

*2021-10-20*

Hi

### 5/5 — UI is actually intuitive

*2019-05-28, version 1.2*

I don’t work in CAD/CAM/modeling. But it has always fascinated me. This app is beautiful and easy to work with. It behaves how I’d expect a viewer to work and I can see all the things I might want to see in every way I might want to see it.

### 3/5 — Can’t open samples: “Error: the system is running low on memory. Operation aborted”

*2017-12-15, version 0.9*

Update: after force closing the app and reopening it, it successfully opens it’s sample files. This doesn’t change the fact that it’s left a very bad first impression with the “out of memory bug” which degrades trust in the app’s reliability as a whole. Also the items are difficult to reliably rotate in 3D, leading to lots of dragging in circles trying to get the model upright again. It also needs to be updated for the iPhone X.

Original review:
This app can’t even open it’s included sample files, it consistently fails, giving the error message “Error: the system is running out of memory, the operation has been aborted!” This is on an iPhone X, so it’s clearly not a problem of an old device with limited RAM, but a buggy, nonfunctional app. Deleted.

## Frequently asked questions about CAD Assistant

### What file formats does CAD Assistant support for viewing?

CAD Assistant supports BREP, IGES, STEP for CAD models, and STL, PLY, OBJ, JT, glTF for mesh models. This allows for a wide range of compatibility with different 3D data.

### Can I convert CAD models to different formats with CAD Assistant?

Yes, CAD Assistant allows you to export CAD models to STEP, IGES, or BREP formats, and mesh models to PLY, STL, OBJ, or glTF formats. You can also save the current view as a PNG image.

### Does CAD Assistant work offline?

Yes, CAD Assistant is designed to work offline, meaning you can view and convert your 3D CAD and mesh models without an internet connection. Files can be opened from local storage or other applications.

### How does CAD Assistant handle complex assemblies?

You can navigate the assembly structure of models through a tree browser in CAD Assistant. Components can be hidden or shown to inspect specific parts of the assembly.

### Is CAD Assistant suitable for users of all ages?

CAD Assistant has an age rating of 4+, making it suitable for a broad audience. Its intuitive interface and focus on technical viewing are geared towards professionals and students.

### How often is CAD Assistant updated?

The latest version of CAD Assistant is 1.2, which was last updated on November 9, 2018. While updates may not be frequent, the core functionality remains robust.

### What devices can I use CAD Assistant on?

CAD Assistant is available for iPhone, iPad, and iPod devices. It is optimized for multi-touch screens to provide an intuitive user experience.

### Does CAD Assistant have ads?

No, CAD Assistant does not contain advertisements. It is a completely free application without any ad interruptions.

## Version history (last 5 releases)

### 1.2 — 2018-11-09

- glTF writer now exports into 2.0 version of this format.
- Option to rename a selected assembly part.
- Improved performance of Flat Shaded and Mesh Shrinked presentation modes.
- Improved robustness of dimensions import from STEP file.
- Improved selection performance in several worst cases.
- Fixed issue with hanging clipping plane presentation on big models.
- Fixed applying length units while reading VRML 2.0 files.

### 1.1 — 2018-08-14

- New languages for user interface: French, Russian.
- New cad import formats (DXF, ACIS) using OCC Commercial Components.
- New mesh import formats (WRL1, BLEND, 3MF, 3DM, 3DS, AC3D, AMF, ASE, COLLADA, X3D).
- Dimensions and tolerances information stored in STEP file is now displayed in 3D Viewer.
- Extensions and bug-fixes for selected object properties.
- Improved stability while reading OBJ and JT files.
- Fixed reading files with GLB extension on iOS.
- Fixed issue when object color cannot be unset.

### 1.0 — 2018-03-06

- Improved support of measurement units.
- Rubber-band selection tool.
- Option to export into Binary glTF 1.0 format.
- Option to exclude normals when exporting to PLY.
- Fixed reading some glTF 2.0 models - byteOffset is now optional.
- OBJ file import compatibility improvements.
- OBJ file export bug-fixes (random failures saving MTL file).
- Fixed handling of transformations and colors assigned to root elements and part instances in the document.

### 0.9 — 2017-04-24

- Support of JT (without LODs), OFF, OBJ and glTF mesh formats.
- Improved performance while displaying big assemblies.
- Improved robustness and performance of reading STL files in text (ASCII) format; option to control nodes merging for STL mesh import.
- Support of polygons with more then 4 nodes within mesh import.
- Option to import multiple models into single document.
- Tool to delete assembly parts.
- Tool to change color of selected parts.
- Clipping planes in 3d view allowing to see the model cross-section and interior.
- Stereoscopic output (interlaced, anaglyph, side-by-side, etc.)

### 0.5 — 2015-06-14

No release notes.

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-07-25.*