# Prolog vs Shift Pair

The clearest difference is in-app purchases: Prolog at none against Shift Pair's 4. On price, ads, device support and iOS requirement there is nothing between them.

Both are free to download. Shift Pair sells 4 in-app purchases, starting at $2.99 per 7 days. Prolog asks for nothing beyond the download.

## The numbers

| Metric | Prolog | Shift Pair |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 2 days | — |
| Size | 55 MB | 18 MB |
| Requires iOS | 17.6 | **17.0** |
| Devices | **iPhone, iPad** | iPhone |
| Age rating | 4+ | 4+ |
| Developer | [Elever (CA)](https://appshunter.io/developer/1769030097) | [凤英 刘](https://appshunter.io/developer/1822180550) |

## What reviewers say

### Prolog

[App page](https://appshunter.io/ios/app/prolog-screen-time-and-focus/id6695728427)

**Features:** macOS Compatibility

**In-app purchases:** none


### Shift Pair

[App page](https://appshunter.io/ios/app/shift-pair-rota-calendar/id6797206830)

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

**In-app purchases (4)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Weekly Pro Access | $2.99 | per 7 days |
| Shift Pair Pro Weekly Trial | $2.99 | per 7 days |
| Monthly Pro Access | $6.99 | per month |
| Yearly Pro Access | $24.99 | per year |


## Frequently asked questions

### Is Prolog free?

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

### Is Shift Pair free?

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

### Do Prolog or Shift Pair have ads?

Neither Prolog nor Shift Pair 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.*