# Dirac equation vs Phobias Guide..

The clearest difference is in-app purchases: Dirac equation at none against Phobias Guide..'s 2. Dirac equation also leads on ads (none vs shown). Phobias Guide..'s advantage is iOS requirement (13.0 vs 17). On price and device support there is nothing between them.

Both are free to download. Phobias Guide.. sells 2 in-app purchases, starting at $1.99 per month. Dirac equation asks for nothing beyond the download.

## The numbers

| Metric | Dirac equation | Phobias Guide.. |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | **No** | Yes |
| Ads | **No** | Yes |
| Update frequency | — | Every 2 weeks |
| Size | 5 MB | 156 MB |
| Requires iOS | 17 | **13.0** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Sungjun Kim](https://appshunter.io/developer/1602461985) | [Olga Ivanova](https://appshunter.io/developer/1733570435) |

## What reviewers say

### Dirac equation

[App page](https://appshunter.io/ios/app/dirac-equation/id6739155551)

**Features:** macOS Compatibility

**In-app purchases:** none


### Phobias Guide..

[App page](https://appshunter.io/ios/app/phobias-guide/id6742685294)

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

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| phobias_by_oliva_subscription | $1.99 | per month |
| phobias_by_oliva_donation | $1.99 | one-time |


## Frequently asked questions

### Is Dirac equation free?

Dirac equation is free to download, with no in-app purchases.

### Is Phobias Guide.. free?

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

### Do Dirac equation or Phobias Guide.. have ads?

Phobias Guide.. shows ads; Dirac equation does not.

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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.*