# JJY Simulator vs AtomicClock

The clearest difference is rating: AtomicClock at 4.8 against JJY Simulator's 4.2. AtomicClock also leads on update cadence (every 3 weeks vs every 66 months) and ratings volume (5.5K vs 18). JJY Simulator's advantage is in-app purchases (none vs 1) and ads (none vs shown). On price and device support there is nothing between them.

Both are free to download. AtomicClock sells 1 one-off in-app purchase. JJY Simulator asks for nothing beyond the download.

AtomicClock holds the better App Store score, 4.8 against 4.2. That said, the two scores are not equally well evidenced: AtomicClock has 5.5K ratings behind it against 18, so its average is the more settled of the two. Written reviews point the same way: 60% of JJY Simulator's written reviews are positive against 84% of AtomicClock's.

JJY Simulator ships an update every 66 months, AtomicClock every 3 weeks. The most recent releases landed on October 7, 2026 and October 14, 2026 respectively.

## The numbers

| Metric | JJY Simulator | AtomicClock |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [4.2 (18 ratings)](https://appshunter.io/ios/app/jjy-simulator/id431054911/reviews) | **[4.8 (5.5K ratings)](https://appshunter.io/ios/app/atomicclock-ntp-time/id1402993049/reviews)** |
| Number of ratings | 18 | **5.5K** |
| Positive reviews | 60.0% of reviews | **84.2% of reviews** |
| In-app purchases | **No** | Yes |
| Ads | **No** | Yes |
| Update frequency | Every 66 months | **Every 3 weeks** |
| Monetization | **Free** | Free with in-app purchases |
| Size | 1 MB | 17 MB |
| Requires iOS | **8.0** | 15.0 |
| Devices | iPhone, iPod | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [NeoCat](https://appshunter.io/developer/431054914) | [Timo Partl](https://appshunter.io/developer/1387413672) |

## 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


### AtomicClock

[App page](https://appshunter.io/ios/app/atomicclock-ntp-time/id1402993049)

This app displays the exact current time synchronized with NTP servers, offering a customizable clock view for precise time checks. It's ideal for setting watches, verifying timestamps, or comparing local and network time.

**Highlights:** Precise time from NTP servers, Customizable clock faces, Select or add time servers, Local and UTC views, 12/24 hour modes, Customizable time format, Acoustic ticking

**Features:** macOS Compatibility

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Lifetime Pro Version | $6.99 | one-time |

**What reviewers like**

- 🚀 Accurate time
- 👍 Highly customizable
- 🚀 Precise to the second
- 👍 Easy to use
- 👍 Helpful for setting watches

**What reviewers complain about**

- 🐛 Server connection issues
- 🔍 Limited time zone options
- 💰 Ads diminish clock view
- 🔍 Lacks some advanced features
- 🔍 Redundant for some users

**Reported bugs**

- Crashes on certain iOS versions
- Occasional freezing of hands
- Countdown timer sound not working

**Requested features**

- Add GMT/dual time display
- Implement widget support
- Add different second hand sounds
- Allow setting background color to match watch
- Include alarm/timer functionality


## Frequently asked questions

### Is JJY Simulator free?

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

### Is AtomicClock free?

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

### Which has better reviews, JJY Simulator or AtomicClock?

AtomicClock is rated higher. JJY Simulator averages 4.2 out of 5 from 18 ratings, while AtomicClock averages 4.8 from 5.5K ratings.

### Do JJY Simulator or AtomicClock have ads?

AtomicClock shows ads; JJY Simulator does not.

### Which is updated more often, JJY Simulator or AtomicClock?

JJY Simulator ships an update every 66 months, and AtomicClock every 3 weeks. Most recently, JJY Simulator was updated on October 7, 2026 and AtomicClock on October 14, 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.*