# Hydraulic Engineer vs 3D Model Viewer & Converter

The clearest difference is price: 3D Model Viewer & Converter at Free against Hydraulic Engineer's $4.99. 3D Model Viewer & Converter also leads on update cadence (every 3 weeks vs every 6 months) and review sentiment (43% vs 25%). Hydraulic Engineer's advantage is rating (4.0 vs 1.5). On ratings volume, ads, in-app purchases and device support there is nothing between them.

3D Model Viewer & Converter is free to download; Hydraulic Engineer costs $4.99 up front. Hydraulic Engineer sells 1 one-off in-app purchase and 3D Model Viewer & Converter sells 10 in-app purchases, starting at $2.99 per 7 days. Whichever you choose, the download price is not the number that matters.

Hydraulic Engineer holds the better App Store score, 4.0 against 1.5. Both are backed by a comparable volume of ratings — 1 and 2 respectively. Written reviews complicate that: 25% of Hydraulic Engineer's written reviews are positive against 43% of 3D Model Viewer & Converter's, so the app with the better star average is not the one people write more warmly about.

Hydraulic Engineer ships an update every 6 months, 3D Model Viewer & Converter every 3 weeks. The most recent releases landed on November 1, 2026 and November 8, 2026 respectively.

## The numbers

| Metric | Hydraulic Engineer | 3D Model Viewer & Converter |
| --- | --- | --- |
| Price | $4.99 | **Free** |
| Rating | **[4.0 (1 ratings)](https://appshunter.io/ios/app/hydraulic-engineer/id410465591/reviews)** | [1.5 (2 ratings)](https://appshunter.io/ios/app/3d-model-viewer-and-converter/id6748610196/reviews) |
| Number of ratings | 1 | **2** |
| Positive reviews | 25.0% of reviews | **42.9% of reviews** |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | Every 6 months | **Every 3 weeks** |
| Monetization | Paid | **Free with in-app purchases** |
| Size | 19 MB | 18 MB |
| Requires iOS | 18.6 | **16.0** |
| Devices | iPhone, iPad | **iPhone, iPad, Mac** |
| Age rating | 4+ | 4+ |
| Developer | [Historycentral.com](https://appshunter.io/developer/1744330560) | [维 艾](https://appshunter.io/developer/1771300149) |

## What reviewers say

### Hydraulic Engineer

[App page](https://appshunter.io/ios/app/hydraulic-engineer/id410465591)

This comprehensive calculator app offers over 1,000 hydraulic engineering formulas across 13 categories. It includes temperature conversions, reference tables, and the ability to save and share calculations. Works offline and supports both US Customary and SI Metric units.

**Highlights:** Over 1,000 hydraulic formulas, 13 specialized calculator categories, Temperature scale converters, Professional reference tables, Save and share calculations, Works offline, US Customary and SI Metric units

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Hydraulic Pro | $3.99 | one-time |


### 3D Model Viewer & Converter

[App page](https://appshunter.io/ios/app/3d-model-viewer-and-converter/id6748610196)

Inspect, convert, and export 3D models with a range of import and export formats. Features include cross-section slicing, exploded views, and orthographic projections. Works offline and keeps files local for a streamlined workflow.

**Highlights:** Import diverse 3D and point cloud formats, Inspect model information summary, Slice cross-sections for internal geometry review, Use exploded view for assembly inspection, Generate orthographic projection outputs, Batch convert multiple files, Basic editing tools: move, rotate, scale

**Features:** Family Sharing, Vision Pro support, iPhone Duo support

**In-app purchases (10)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Pro Flex | $2.99 | per 7 days |
| Pro Light | $9.99 | per month |
| Pro Infinity | $59.99 | per year |
| Export as PNG | $2.99 | one-time |
| Export as OBJ | $3.99 | one-time |
| Export as USDZ | $3.99 | one-time |
| Export as STL | $3.99 | one-time |
| Unlock Projection View Export | $4.99 | one-time |
| Cross Section View | $6.99 | one-time |
| Export all formats | $16.99 | one-time |


## Frequently asked questions

### Is Hydraulic Engineer free?

Hydraulic Engineer costs $4.99, and also offers in-app purchases.

### Is 3D Model Viewer & Converter free?

3D Model Viewer & Converter is free to download, with in-app purchases available.

### Which has better reviews, Hydraulic Engineer or 3D Model Viewer & Converter?

Hydraulic Engineer is rated higher. Hydraulic Engineer averages 4.0 out of 5 from 1 ratings, while 3D Model Viewer & Converter averages 1.5 from 2 ratings.

### Do Hydraulic Engineer or 3D Model Viewer & Converter have ads?

Neither Hydraulic Engineer nor 3D Model Viewer & Converter shows ads.

### Which is updated more often, Hydraulic Engineer or 3D Model Viewer & Converter?

Hydraulic Engineer ships an update every 6 months, and 3D Model Viewer & Converter every 3 weeks. Most recently, Hydraulic Engineer was updated on November 1, 2026 and 3D Model Viewer & Converter on November 8, 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.*