# mechanical design engine vs Digital_Diary

The clearest difference is in-app purchases: mechanical design engine at none against Digital_Diary's 2. Digital_Diary's advantage is update cadence (every 2 days vs every 2 months) and device support (4 vs 2). On price, ads and iOS requirement there is nothing between them.

Both are free to download. Digital_Diary sells 2 in-app purchases, starting at $19.99 per month. mechanical design engine asks for nothing beyond the download.

mechanical design engine ships an update every 2 months, Digital_Diary every 2 days. The most recent releases landed on October 11, 2026 and October 10, 2026 respectively.

## The numbers

| Metric | mechanical design engine | Digital_Diary |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 2 months | **Every 2 days** |
| Size | 63 MB | 3 MB |
| Requires iOS | 13.0 | 13.0 |
| Devices | iPhone, iPod | **iPhone, iPad, iPod, Mac** |
| Age rating | 4+ | 4+ |
| Developer | [gan dae choi](https://appshunter.io/developer/1574341439) | [Shabbir Ahmed](https://appshunter.io/developer/1083166021) |

## What reviewers say

### mechanical design engine

[App page](https://appshunter.io/ios/app/mechanical-design-engine/id1574341437)

**Features:** macOS Compatibility

**In-app purchases:** none


### Digital_Diary

[App page](https://appshunter.io/ios/app/digital-diary/id6478133027)

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Monthly Auto-Renewing Subs | $19.99 | per month |
| Annual Auto-Renewing Subs | $24.99 | per year |


## Frequently asked questions

### Is mechanical design engine free?

mechanical design engine is free to download, with no in-app purchases.

### Is Digital_Diary free?

Digital_Diary is free to download, with in-app purchases available.

### Do mechanical design engine or Digital_Diary have ads?

Neither mechanical design engine nor Digital_Diary shows ads.

### Which is updated more often, mechanical design engine or Digital_Diary?

mechanical design engine ships an update every 2 months, and Digital_Diary every 2 days. Most recently, mechanical design engine was updated on October 11, 2026 and Digital_Diary on October 10, 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.*