# Fast Clock vs Otosan

The clearest difference is review sentiment: Otosan at 100% against Fast Clock's 25%. Fast Clock's advantage is update cadence (every 2 days vs weekly) and iOS requirement (15.6 vs 26.2). On price, ads, in-app purchases and monetization model there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

Fast Clock ships an update every 2 days, Otosan weekly. The most recent releases landed on November 3, 2026 and November 5, 2026 respectively.

## The numbers

| Metric | Fast Clock | Otosan |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[3.8 (5 ratings)](https://appshunter.io/ios/app/fast-clock/id6448879724/reviews)** | — |
| Number of ratings | **5** | — |
| Positive reviews | 25.0% of reviews | **100.0% of reviews** |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | **Every 2 days** | Weekly |
| Monetization | Free | Free |
| Size | 5 MB | 102 MB |
| Requires iOS | **15.6** | 26.2 |
| Devices | **iPhone, iPod** | iPhone |
| Age rating | 4+ | 4+ |
| Developer | [Kevin Snow](https://appshunter.io/developer/305581830) | [HIROSHI SHINKAWA](https://appshunter.io/developer/1875457585) |

## What reviewers say

### Fast Clock

[App page](https://appshunter.io/ios/app/fast-clock/id6448879724)

This application simulates a fast clock for model railroads. It allows for custom logos and maps, and can synchronize with external systems like JMRI or use real-time.

**Highlights:** Model railroad fast clock simulation, Custom logo support, Custom map integration, JMRI time synchronization, Real-time clock option

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

**In-app purchases:** none


### Otosan

[App page](https://appshunter.io/ios/app/otosan/id6758872739)

Generate any sound frequency between 20Hz and 20,000Hz for relaxation, meditation, or testing hearing. Includes a simple instrument tuner and bonus tracks.

**Highlights:** Adjustable frequency generator (20Hz-20,000Hz), Hearing range testing, Instrument tuner, Supports popular relaxation frequencies (432Hz, 528Hz), Includes bonus audio tracks

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

**In-app purchases:** none


## Frequently asked questions

### Is Fast Clock free?

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

### Is Otosan free?

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

### Do Fast Clock or Otosan have ads?

Neither Fast Clock nor Otosan shows ads.

### Which is updated more often, Fast Clock or Otosan?

Fast Clock ships an update every 2 days, and Otosan weekly. Most recently, Fast Clock was updated on November 3, 2026 and Otosan on November 5, 2026.

---

*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*