Comparison

AtomicClock vs SkyAtlas

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

Head to head
About

AtomicClock

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
Read full description

Check precise NTP reference time at a glance. AtomicClock helps you set watches, wall clocks, cameras, and other devices, compare local time with UTC, and follow moments when every second matters. Clear analog and digital time AtomicClock displays current time from NTP servers that reference atomic clocks. Choose a predefined server or add your own, then view local or UTC time in a clean analog or digital clock. Customize your reference clock • Switch between 12-hour and 24-hour time • Customize the time format • Choose from multiple clock faces and hands • Use a smooth, fluid second hand • Add acoustic ticking or the Greenwich Time Signal • Tap the screen to hide information and controls, freeze the display, or mute ticking Details for precise time checks View technical NTP information, including round-trip time and server stratum. Whether you are checking a timestamp, preparing a camera, aligning a wall clock, or setting a watch by hand, the seconds remain clear and easy to follow. AtomicClock is free to use. AtomicClock Pro is available as a one-time purchase with no subscription. It unlocks your preferred clock face, hands, and font, removes ads, and includes upcoming Pro features. AtomicClock displays NTP reference time for comparison and does not change your device’s system time. Results can vary with the selected server, network conditions, and device behavior.

About

SkyAtlas

Explore the night sky with a digital atlas and control your telescope mount. Plan astrophotography compositions with simulated camera fields of view and track celestial objects in real-time. Features one-click GoTo and mode switching for an enhanced stargazing experience.

Highlights
  • Digital sky atlas exploration
  • Telescope mount control (ZWO ASI)
  • Simulated camera field of view
  • Real-time telescope pointing display
  • One-click GoTo functionality
  • Object tracking
  • EQ and AltAz mode switching
Features
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SkyAtlas is the control app for ZWO AM series mounts, with Bluetooth support for ZWO EAF. Use your phone to control the mount and focuser with ease. The built-in star map includes thousands of stars and deep-sky objects. "Best Tonight" recommends the best targets in your current sky. Tap GoTo, and the mount automatically tracks your chosen object. Preview your telescope's aim and frame shots right on your screen—what you see is where it points. Switch between equatorial and alt-az modes with one tap. SkyAtlas, explore the night sky, simplified.

Screenshots

AtomicClock4 screens
SkyAtlas4 screens

Verdict

The call

The clearest difference is review sentiment: AtomicClock at 84% against SkyAtlas's 40%. AtomicClock also leads on rating (4.8 vs 2.4) and ratings volume (5.6K vs 17). SkyAtlas's advantage is in-app purchases (none vs 1) and ads (none vs shown). On price, update cadence 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. AtomicClock sells 1 one-off in-app purchase. SkyAtlas asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

AtomicClock holds the better App Store score, 4.8 against 2.4. That said, the two scores are not equally well evidenced: AtomicClock has 5.6K ratings behind it against 17, so its average is the more settled of the two. Written reviews point the same way: 84% of AtomicClock's written reviews are positive against 40% of SkyAtlas's.

UpkeepUpdate frequency

Both ship on a similar rhythm, roughly monthly. The most recent releases landed on October 19, 2026 and October 10, 2026 respectively.

Scorecard7 real differences · 3 level
AtomicClock versus SkyAtlas: the parameters behind the verdict, then further details
ParameterAtomicClockSkyAtlas
PriceFreeFree
Rating4.8 (5.6K ratings) — better2.4 (17 ratings)
Positive reviews84.3% of reviews — better40.0% of reviews
Number of ratings5.6K — better17
Update frequencyMonthlyMonthly
AdsYesNo — better
In-app purchasesYesNo — better
MonetizationFree with in-app purchasesFree — better
DevicesiPhone, iPadiPhone, iPad, iPod — better
Requires iOS17.411.0 — better
Further details — not scored
Size17 MB911 MB
Age rating4+4+
DeveloperTimo PartlSuZhou ZWO Co., Ltd

Customer experience

AtomicClock

All ratings5,568 ratings
Positive96.5%
Neutral1.7%
Negative1.8%
Written reviews242 reviews
Positive84.3%
Neutral3.3%
Negative12.4%

SkyAtlas

All ratings17 ratings
Positive29.4%
Neutral5.9%
Negative64.7%
Written reviews10 reviews
Positive40.0%
Neutral10.0%
Negative50.0%

Bugs and requests

AtomicClock

Reported bugs

3 issues
  • Crashes on certain iOS versions
  • Occasional freezing of hands
  • Countdown timer sound not working

Requested features

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

SkyAtlas

Not enough reviews yet to summarise bugs or requests.

In-app purchases

1 purchases

AtomicClock

One-time1
  • Lifetime Pro Version$6.99
None

SkyAtlas

No in-app purchases

Questions

Is AtomicClock free?
AtomicClock is free to download, with in-app purchases available.
Is SkyAtlas free?
SkyAtlas is free to download, with no in-app purchases.
Which has better reviews, AtomicClock or SkyAtlas?
AtomicClock is rated higher. AtomicClock averages 4.8 out of 5 from 5.6K ratings, while SkyAtlas averages 2.4 from 17 ratings.
Do AtomicClock or SkyAtlas have ads?
AtomicClock shows ads; SkyAtlas does not.
Which is updated more often, AtomicClock or SkyAtlas?
AtomicClock ships an update monthly, and SkyAtlas monthly. Most recently, AtomicClock was updated on October 19, 2026 and SkyAtlas on October 10, 2026.

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