# AtomicClock vs NASA SpaceTime

The clearest difference is in-app purchases: NASA SpaceTime at none against AtomicClock's 1. NASA SpaceTime also leads on ads (none vs shown) and review sentiment (100% vs 84%). AtomicClock's advantage is ratings volume (5.5K vs 6). On price, update cadence and iOS requirement there is nothing between them.

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

NASA SpaceTime holds the better App Store score, 5.0 against 4.8. That said, the two scores are not equally well evidenced: AtomicClock has 5.5K ratings behind it against 6, 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 100% of NASA SpaceTime's.

AtomicClock ships an update every 3 weeks, NASA SpaceTime every 4 weeks. The most recent releases landed on October 17, 2026 and October 3, 2026 respectively.

## The numbers

| Metric | AtomicClock | NASA SpaceTime |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [4.8 (5.5K ratings)](https://appshunter.io/ios/app/atomicclock-ntp-time/id1402993049/reviews) | **[5.0 (6 ratings)](https://appshunter.io/ios/app/nasa-spacetime/id1553555795/reviews)** |
| Number of ratings | **5.5K** | 6 |
| Positive reviews | 84.2% of reviews | **100.0% of reviews** |
| In-app purchases | Yes | **No** |
| Ads | Yes | **No** |
| Update frequency | **Every 3 weeks** | Every 4 weeks |
| Monetization | Free with in-app purchases | **Free** |
| Size | 17 MB | 38 MB |
| Requires iOS | 15.0 | **14.0** |
| Devices | iPhone, iPad, iPod | **iPhone, iPad, iPod, Mac, Apple Watch** |
| Age rating | 4+ | 4+ |
| Developer | [Timo Partl](https://appshunter.io/developer/1387413672) | [Jet Propulsion Laboratory](https://appshunter.io/developer/347075767) |

## What reviewers say

### 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


### NASA SpaceTime

[App page](https://appshunter.io/ios/app/nasa-spacetime/id1553555795)

Track the current time on Mars for NASA's Perseverance and Curiosity rovers. View mission event schedules and operational meetings. Supports Siri integration for quick time queries.

**Highlights:** Mars time display, Earth time display, Rover mission schedules, Operational meeting views, Siri integration

**In-app purchases:** none


## Frequently asked questions

### Is AtomicClock free?

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

### Is NASA SpaceTime free?

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

### Which has better reviews, AtomicClock or NASA SpaceTime?

NASA SpaceTime is rated higher. AtomicClock averages 4.8 out of 5 from 5.5K ratings, while NASA SpaceTime averages 5.0 from 6 ratings.

### Do AtomicClock or NASA SpaceTime have ads?

AtomicClock shows ads; NASA SpaceTime does not.

### Which is updated more often, AtomicClock or NASA SpaceTime?

AtomicClock ships an update every 3 weeks, and NASA SpaceTime every 4 weeks. Most recently, AtomicClock was updated on October 17, 2026 and NASA SpaceTime on October 3, 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.*