# D426 Mastery vs Database Keys and Constraints

The clearest difference is in-app purchases: Database Keys and Constraints at none against D426 Mastery's 2. Database Keys and Constraints also leads on iOS requirement (15.1 vs 17.6). On price, ads and device support there is nothing between them.

Both are free to download. D426 Mastery sells 2 in-app purchases, starting at $7.99 per month. Database Keys and Constraints asks for nothing beyond the download.

## The numbers

| Metric | D426 Mastery | Database Keys and Constraints |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Size | 4 MB | 38 MB |
| Requires iOS | 17.6 | **15.1** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [JOHN TIMOTHY DISALLE](https://appshunter.io/developer/1886538582) | [AFTW LLC](https://appshunter.io/developer/1886356149) |

## What reviewers say

### D426 Mastery

[App page](https://appshunter.io/ios/app/d426-mastery/id6761743682)

**Features:** macOS Compatibility

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Monthly Premium | $7.99 | per month |
| Lifetime Access | $24.99 | one-time |


### Database Keys and Constraints

[App page](https://appshunter.io/ios/app/database-keys-and-constraints/id6773622183)

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

**In-app purchases:** none


## Frequently asked questions

### Is D426 Mastery free?

D426 Mastery is free to download, with in-app purchases available.

### Is Database Keys and Constraints free?

Database Keys and Constraints is free to download, with no in-app purchases.

### Do D426 Mastery or Database Keys and Constraints have ads?

Neither D426 Mastery nor Database Keys and Constraints shows ads.

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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.*