# Merge Object Viewer vs HMH Science Dimensions

The clearest difference is rating: Merge Object Viewer at 4.5 against HMH Science Dimensions's 2.3. Merge Object Viewer also leads on review sentiment (48% vs 25%) and ratings volume (389 vs 17). HMH Science Dimensions's advantage is in-app purchases (none vs 4) and iOS requirement (9.0 vs 15.0). On price, update cadence, ads and device support there is nothing between them.

Both are free to download. Merge Object Viewer sells 4 in-app purchases, starting at $9.99 per month. HMH Science Dimensions asks for nothing beyond the download.

Merge Object Viewer holds the better App Store score, 4.5 against 2.3. That said, the two scores are not equally well evidenced: Merge Object Viewer has 389 ratings behind it against 17, so its average is the more settled of the two. Written reviews point the same way: 48% of Merge Object Viewer's written reviews are positive against 25% of HMH Science Dimensions's.

Merge Object Viewer ships an update monthly, HMH Science Dimensions every 2 months. The most recent releases landed on October 22, 2026 and October 21, 2026 respectively.

## The numbers

| Metric | Merge Object Viewer | HMH Science Dimensions |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.5 (389 ratings)](https://appshunter.io/ios/app/merge-object-viewer/id1367544362/reviews)** | [2.3 (17 ratings)](https://appshunter.io/ios/app/hmh-science-dimensions/id1384935325/reviews) |
| Number of ratings | **389** | 17 |
| Positive reviews | **47.6% of reviews** | 25.0% of reviews |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | **Monthly** | Every 2 months |
| Monetization | Free with in-app purchases | **Free** |
| Size | 414 MB | 227 MB |
| Requires iOS | 15.0 | **9.0** |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Merge Apps](https://appshunter.io/developer/1253049593) | [Houghton Mifflin Harcourt](https://appshunter.io/developer/409368007) |

## What reviewers say

### Merge Object Viewer

[App page](https://appshunter.io/ios/app/merge-object-viewer/id1367544362)

Explore hundreds of 3D digital teaching aids with this app. Students can interact with models of rocks, mammals, cells, and more. The app also allows users to upload and view their own 3D objects on a compatible device.

**Highlights:** Hundreds of 3D teaching aids, Interactive 3D models, Learn about science and biology, Upload and view custom 3D objects, Hands-on digital learning

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

**In-app purchases (4)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Object Viewer Premium Monthly | $9.99 | per month |
| Merge EDU Individual | $9.99 | per month |
| Object Viewer Premium Annual | $99.99 | per year |
| Merge EDU Individual | $99.99 | per year |

**What reviewers like**

- 🚀 Engaging AR STEM tool
- 👍 Intuitive interface
- 👍 Seamless object merging
- 👍 Extensive file format support
- 👍 Convenient sharing options

**What reviewers complain about**

- 🐛 Frequent crashes
- 🐛 Slow rendering/loading
- 🐛 Compatibility issues on older devices
- 🔒 Paywall for full access
- 🐛 Unstable login/account management

**Reported bugs**

- Objects not loading or displaying incorrectly
- App freezing or closing unexpectedly
- Labeling/annotation issues with 3D objects
- Compatibility problems on iPads and older iOS versions

**Requested features**

- Adjustable lighting for 3D objects
- Ability to snap objects together
- Camera button for capturing scenes
- Restore VR support
- More free 3D content options


### HMH Science Dimensions

[App page](https://appshunter.io/ios/app/hmh-science-dimensions/id1384935325)

This augmented reality app transforms book covers into interactive science experiments. Students can scan their textbooks to launch 3D models and explore concepts like weather, solar energy, and the solar system. It's designed to make learning engaging and fun for young students.

**Highlights:** Augmented reality science experiments, Scan book covers to activate content, Interactive 3D models, Explores various science topics, Engaging learning experience, Group or pair work friendly

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is Merge Object Viewer free?

Merge Object Viewer is free to download, with in-app purchases available.

### Is HMH Science Dimensions free?

HMH Science Dimensions is free to download, with no in-app purchases.

### Which has better reviews, Merge Object Viewer or HMH Science Dimensions?

Merge Object Viewer is rated higher. Merge Object Viewer averages 4.5 out of 5 from 389 ratings, while HMH Science Dimensions averages 2.3 from 17 ratings.

### Do Merge Object Viewer or HMH Science Dimensions have ads?

Neither Merge Object Viewer nor HMH Science Dimensions shows ads.

### Which is updated more often, Merge Object Viewer or HMH Science Dimensions?

Merge Object Viewer ships an update monthly, and HMH Science Dimensions every 2 months. Most recently, Merge Object Viewer was updated on October 22, 2026 and HMH Science Dimensions on October 21, 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.*