# Model Scaler vs STL Simple Viewer

The clearest difference is rating: STL Simple Viewer at 4.3 against Model Scaler's 2.9. STL Simple Viewer also leads on ratings volume (866 vs 12). Model Scaler's advantage is in-app purchases (none vs 4) and ads (none vs shown). On price and device support 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. Model Scaler asks for nothing beyond the download.

STL Simple Viewer holds the better App Store score, 4.3 against 2.9. That said, the two scores are not equally well evidenced: STL Simple Viewer has 866 ratings behind it against 12, so its average is the more settled of the two. Written reviews complicate that: 40% of Model Scaler's written reviews are positive against 17% of STL Simple Viewer's, so the app with the better star average is not the one people write more warmly about.

Model Scaler ships an update every 6 months, STL Simple Viewer every 20 months. The most recent releases landed on June 11, 2026 and September 23, 2026 respectively.

## The numbers

| Metric | Model Scaler | STL Simple Viewer |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [2.9 (12 ratings)](https://appshunter.io/ios/app/model-scaler/id528641484/reviews) | **[4.3 (866 ratings)](https://appshunter.io/ios/app/stl-simple-viewer/id1493598400/reviews)** |
| Number of ratings | 12 | **866** |
| Positive reviews | **40.0% of reviews** | 17.2% of reviews |
| In-app purchases | **No** | Yes |
| Ads | **No** | Yes |
| Update frequency | **Every 6 months** | Every 20 months |
| Monetization | **Free** | Free with in-app purchases |
| Size | 11 MB | 19 MB |
| Requires iOS | **9.0** | 17.0 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | +4 |
| Developer | [Woodland Scenics](https://appshunter.io/developer/528641487) | [Victor Bovio](https://appshunter.io/developer/327627515) |

## What reviewers say

### Model Scaler

[App page](https://appshunter.io/ios/app/model-scaler/id528641484)

This tool instantly converts measurements between U.S. Customary and Metric units for any modeling scale. It's designed to be fast, easy, and efficient for all types of scale modelers.

**Highlights:** Instant scale conversion, U.S. Customary to Metric, Metric to U.S. Customary, Supports any modeling scale, Fast and efficient

**Features:** macOS Compatibility

**In-app purchases:** none


### 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


## Frequently asked questions

### Is Model Scaler free?

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

### Is STL Simple Viewer free?

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

### Which has better reviews, Model Scaler or STL Simple Viewer?

STL Simple Viewer is rated higher. Model Scaler averages 2.9 out of 5 from 12 ratings, while STL Simple Viewer averages 4.3 from 866 ratings.

### Do Model Scaler or STL Simple Viewer have ads?

STL Simple Viewer shows ads; Model Scaler does not.

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

Model Scaler ships an update every 6 months, and STL Simple Viewer every 20 months. Most recently, Model Scaler was updated on June 11, 2026 and STL Simple Viewer on September 23, 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.*