Comparison

JJY Simulator vs Atomic Clock PRO

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

JJY Simulator

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
Read full description

日本で市販されている電波時計をiPhoneで合わせるユーティリティです。 日本の電波時計の基準局(JJY)で使用される標準電波を模擬した信号を、13.3kHzの音声として出力し、3倍高調波(40kHz)を利用して時刻を合わせます。 1. イヤホンをiPhoneのイヤホンジャックに接続し、電波時計のすぐそばに置きます。 2. 音量を最大に設定します。 3. 「音声信号を出力」をオンにします。 4. 電波時計を強制受信モードにし、時刻が合うまで数分間待ちます。

About

Atomic Clock PRO

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
Read full description

Get accurate time on your iPhone and iPad by syncing with an official atomic clock time server. Download now for free! If you want exact time, a precise time reference, or an easy-to-read clock display, this app is designed for that. It automatically recognizes your time zone, lets you use one of your own photos as the background, and lets you switch between a digital display and a classic analog clock with a simple swipe. It is ideal as a personalized desk clock, a reliable travel companion, an everyday reference clock, or when you need exact time to set a mechanical watch accurately. Overview: - Accurate and precise time synced from an official atomic clock time server - Automatically recognizes your time zone and shows the current local time - Choose digital, analog, or combined analog and digital clock displays - Swipe to switch between clock displays - Resize the digital clock for a larger or smaller display - Includes time (hours, minutes, and seconds), date, and day of the week (optional) - Optional sound every second or every minute - Change clock and background colors - Use your own photos as background images - Choose atomic clock sync or your device's system clock - Option to keep the screen awake while the app is open - Works in portrait and landscape mode - For iPhone and iPad Helpful for: - A personalized desk clock at home or at work - Getting the correct local time while traveling - Setting a mechanical watch accurately - A clear reference clock when you want accurate, easy-to-read time PLEASE NOTE: You can switch between the analog and digital clock by swiping left or right across the clock. Disclaimer: Please note that whilst all reasonable care has been taken to make this application as accurate as possible we can not guarantee 100% accuracy. Standard Apple Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/

Screenshots

JJY Simulator2 screens
Atomic Clock PRO4 screens

Verdict

The call

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.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

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.

ReceptionRating · Positive reviews · Number of ratings

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.

UpkeepUpdate frequency

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

Scorecard7 real differences · 3 level
JJY Simulator versus Atomic Clock PRO: the parameters behind the verdict, then further details
ParameterJJY SimulatorAtomic Clock PRO
PriceFreeFree
Rating4.2 (18 ratings)4.7 (10K ratings) — better
Positive reviews68.1% of reviews73.0% of reviews — better
Number of ratings1810K — better
Update frequencyEvery 66 monthsEvery 3 months — better
AdsNo — betterYes
In-app purchasesNo — betterYes
MonetizationFree — betterFree with in-app purchases
DevicesiPhone, iPodiPhone, iPad, iPod — better
Requires iOS8.0 — better15.6
Further details — not scored
Size1 MB6 MB
Age rating4+4+
DeveloperNeoCatBrachmann Online Marketing GmbH & Co. KG

Customer experience

JJY Simulator

All ratings18 ratings
Positive72.2%
Neutral16.7%
Negative11.1%
Written reviews135 reviews
Positive68.1%
Neutral5.9%
Negative25.9%

Atomic Clock PRO

All ratings10,111 ratings
Positive92.3%
Neutral3.5%
Negative4.2%
Written reviews422 reviews
Positive73.0%
Neutral5.9%
Negative21.1%

Bugs and requests

JJY Simulator

Not enough reviews yet to summarise bugs or requests.

Atomic Clock PRO

Reported bugs

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

Requested features

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

In-app purchases

None

JJY Simulator

No in-app purchases

2 purchases

Atomic Clock PRO

Subscriptions1
  • Premium$1.991 Month
One-time1
  • Remove Ads$5.99

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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