# STL Simple Viewer vs ctLibrary

The clearest difference is in-app purchases: ctLibrary at none against STL Simple Viewer's 4. ctLibrary also leads on ads (none vs shown) and update cadence (daily vs every 20 months). On price, device support and iOS requirement there is nothing between them.

Both are free to download. STL Simple Viewer sells 4 in-app purchases, starting at $0.99 per 7 days. ctLibrary asks for nothing beyond the download.

STL Simple Viewer ships an update every 20 months, ctLibrary daily. The most recent releases landed on September 30, 2026 and September 19, 2026 respectively.

## The numbers

| Metric | STL Simple Viewer | ctLibrary |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.3 (866 ratings)](https://appshunter.io/ios/app/stl-simple-viewer/id1493598400/reviews)** | — |
| Number of ratings | **866** | — |
| Positive reviews | 17.2% of reviews | — |
| In-app purchases | Yes | **No** |
| Ads | Yes | **No** |
| Update frequency | Every 20 months | **Daily** |
| Monetization | Free with in-app purchases | — |
| Size | 19 MB | 43 MB |
| Requires iOS | 17.0 | **16.4** |
| Devices | iPhone, iPad | iPhone, iPad |
| Age rating | +4 | 4+ |
| Developer | [Victor Bovio](https://appshunter.io/developer/327627515) | [CozziTech LLC](https://appshunter.io/developer/1881303395) |

## What reviewers say

### STL Simple Viewer

[App page](https://appshunter.io/ios/app/stl-simple-viewer/id1493598400)

Easily view and interact with 3D STL CAD models. Supports various file types and offers advanced rendering options for detailed analysis. Get model information and explore interiors with clipping planes.

**Highlights:** View ASCII and Binary STL files, Load STL from ZIP, Rotate, pan, and zoom, Orthogonal and Perspective modes, Model info (triangle count, bounding box), Rendering options (faces, edges, transparency), Clipping plane for interiors

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases (4)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Pro version (1 week plan) | $0.99 | per 7 days |
| Pro version (1 month plan) | $1.99 | per month |
| Remove Ads | $2.99 | one-time |
| Export to OBJ, DAE, DXF, PLY | $3.99 | one-time |

**What reviewers like**

- 🚀 Simple and intuitive viewer
- 👍 Useful viewing options
- 💡 Supports multiple file formats

**What reviewers complain about**

- 🐛 Frequent crashes
- 🔋 High battery consumption
- 🚨 Excessive and intrusive ads
- 🔍 Limited functionality for larger files

**Reported bugs**

- App crashes when opening larger STL files
- Inability to open some file formats
- Ads continue to appear even after paying for ad removal

**Requested features**

- Add ability to save color/lighting settings
- Improve stability and reduce crashes
- Provide an ad-free paid version


### ctLibrary

[App page](https://appshunter.io/ios/app/ctlibrary/id6773506408)

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases:** none


## Frequently asked questions

### Is STL Simple Viewer free?

STL Simple Viewer is free to download, with in-app purchases available.

### Is ctLibrary free?

ctLibrary is free to download, with no in-app purchases.

### Do STL Simple Viewer or ctLibrary have ads?

STL Simple Viewer shows ads; ctLibrary does not.

### Which is updated more often, STL Simple Viewer or ctLibrary?

STL Simple Viewer ships an update every 20 months, and ctLibrary daily. Most recently, STL Simple Viewer was updated on September 30, 2026 and ctLibrary on September 19, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*