# JJY Simulator vs Atomic Clock PRO

The clearest difference is rating: Atomic Clock PRO at 4.7 against JJY Simulator's 4.2. Atomic Clock PRO also leads on update cadence (every 3 months vs every 66 months) and ratings volume (10K vs 18). JJY Simulator's advantage is in-app purchases (none vs 2) and ads (none vs shown). On price, review sentiment and device support there is nothing between them.

Both are free to download. Atomic Clock PRO sells 2 in-app purchases, starting at $1.99 per month. JJY Simulator asks for nothing beyond the download.

Atomic Clock PRO holds the better App Store score, 4.7 against 4.2. That said, the two scores are not equally well evidenced: Atomic Clock PRO has 10K ratings behind it against 18, so its average is the more settled of the two. Written reviews point the same way: 68% of JJY Simulator's written reviews are positive against 73% of Atomic Clock PRO's.

JJY Simulator ships an update every 66 months, Atomic Clock PRO every 3 months. Both last shipped on October 18, 2026.

## The numbers

| Metric | JJY Simulator | Atomic Clock PRO |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [4.2 (18 ratings)](https://appshunter.io/ios/app/jjy-simulator/id431054911/reviews) | **[4.7 (10K ratings)](https://appshunter.io/ios/app/atomic-clock-pro/id899090224/reviews)** |
| Number of ratings | 18 | **10K** |
| Positive reviews | 68.1% of reviews | **73.0% of reviews** |
| In-app purchases | **No** | Yes |
| Ads | **No** | Yes |
| Update frequency | Every 66 months | **Every 3 months** |
| Monetization | **Free** | Free with in-app purchases |
| Size | 1 MB | 6 MB |
| Requires iOS | **8.0** | 15.6 |
| Devices | iPhone, iPod | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [NeoCat](https://appshunter.io/developer/431054914) | [Brachmann Online Marketing GmbH & Co. KG](https://appshunter.io/developer/682848918) |

## What reviewers say

### JJY Simulator

[App page](https://appshunter.io/ios/app/jjy-simulator/id431054911)

This utility app simulates standard radio waves used by Japanese radio-controlled clocks. It outputs a 13.3kHz audio signal to synchronize your clock, allowing you to manually set the time.

**Highlights:** Simulates JJY standard radio waves, Outputs 13.3kHz audio signal, Synchronizes radio-controlled clocks, Uses 40kHz for time adjustment, Requires earphone connection

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

**In-app purchases:** none


### Atomic Clock PRO

[App page](https://appshunter.io/ios/app/atomic-clock-pro/id899090224)

Get the most accurate time from an official atomic clock server. This app automatically detects your time zone and allows custom backgrounds. Easily switch between digital and analog clock displays with a swipe.

**Highlights:** Exact time from atomic clock, Automatic time zone recognition, Customizable background images, Digital and analog clock modes, Optional sound alerts, Color customization

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

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Premium | $1.99 | per month |
| Remove Ads | $5.99 | one-time |

**What reviewers like**

- ⭐ Accurate time display
- 📟 Useful for timing events
- 🕰️ Helpful for setting other clocks
- 🔍 Large, easy-to-read clock face

**What reviewers complain about**

- 💸 Subscription model for ad-free version
- 📢 Excessive advertisements
- 🔍 Small font for seconds display
- 🔀 Difficulty in displaying both analog and digital clocks simultaneously

**Reported bugs**

- Second hand occasionally runs in reverse
- Digital clock display cuts off on some devices
- Inconsistent behavior when switching between clock types

**Requested features**

- Customizable clock face options
- Ability to set widget on home screen
- Sync with system clock to automatically update time


## Frequently asked questions

### Is JJY Simulator free?

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

### Is Atomic Clock PRO free?

Atomic Clock PRO is free to download, with in-app purchases available.

### Which has better reviews, JJY Simulator or Atomic Clock PRO?

Atomic Clock PRO is rated higher. JJY Simulator averages 4.2 out of 5 from 18 ratings, while Atomic Clock PRO averages 4.7 from 10K ratings.

### Do JJY Simulator or Atomic Clock PRO have ads?

Atomic Clock PRO shows ads; JJY Simulator does not.

### Which is updated more often, JJY Simulator or Atomic Clock PRO?

JJY Simulator ships an update every 66 months, and Atomic Clock PRO every 3 months. Most recently, JJY Simulator was updated on October 18, 2026 and Atomic Clock PRO on October 18, 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.*