# Periscope Watchkeeper vs Master

The clearest difference is price: Master at $1.99 against Periscope Watchkeeper's $14.99. Master also leads on update cadence (fortnightly vs every 19 months). Periscope Watchkeeper's advantage is iOS requirement (12.0 vs 15.0). On review sentiment, ads, in-app purchases and monetization model there is nothing between them.

Periscope Watchkeeper costs $14.99 and Master $1.99 up front. Neither carries in-app purchases, so what you see is what you pay.

Periscope Watchkeeper ships an update every 19 months, Master fortnightly. The most recent releases landed on October 9, 2026 and October 17, 2026 respectively.

## The numbers

| Metric | Periscope Watchkeeper | Master |
| --- | --- | --- |
| Price | $14.99 | **$1.99** |
| Rating | — | **[4.7 (94 ratings)](https://appshunter.io/ios/app/master-nav/id1602390396/reviews)** |
| Number of ratings | — | **94** |
| Positive reviews | **100.0% of reviews** | 96.9% of reviews |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 19 months | **Fortnightly** |
| Monetization | Paid | Paid |
| Size | 131 MB | 117 MB |
| Requires iOS | **12.0** | 15.0 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Dzeba Systems](https://appshunter.io/developer/1517190817) | [Peterjohn Chisholm](https://appshunter.io/developer/1602390398) |

## What reviewers say

### Periscope Watchkeeper

[App page](https://appshunter.io/ios/app/periscope-watchkeeper/id1517198191)

Train your "eyes only" submarine periscope skills with this educational application. It offers various target types, difficulty levels, and guided tutorials to help users refine their observational abilities.

**Highlights:** Multiple target types, Adjustable difficulty levels, Passive Range and Look Interval mode, Night mode, Distance Of Track calculations, Duration Of Attack calculations, Guided tutorials

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

**In-app purchases:** none


### Master

[App page](https://appshunter.io/ios/app/master-nav/id1602390396)

Learn maritime navigation rules with an interactive system designed for effective retention. This app breaks down complex regulations into manageable sections with visual aids and mnemonics. It revisits incorrect answers and provides instant graphical feedback, making the learning process intuitive and efficient.

**Highlights:** Interactive learning system, Step-by-step rule guidance, Mnemonics and memory aids, Interactive visuals, Graphical feedback on answers, Practice section with progress tracking

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

**In-app purchases:** none


## Frequently asked questions

### Is Periscope Watchkeeper free?

Periscope Watchkeeper costs $14.99, with no in-app purchases.

### Is Master free?

Master costs $1.99, with no in-app purchases.

### Do Periscope Watchkeeper or Master have ads?

Neither Periscope Watchkeeper nor Master shows ads.

### Which is updated more often, Periscope Watchkeeper or Master?

Periscope Watchkeeper ships an update every 19 months, and Master fortnightly. Most recently, Periscope Watchkeeper was updated on October 9, 2026 and Master on October 17, 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.*