Comparison

RadioactivityCounter vs Who's in Space?

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

Head to head
About

RadioactivityCounter

Transform your phone into a functional radioactivity counter. Measure gamma and some beta radiation using your device's camera sensor after calibration. Useful for personal use and experimentation with radiation sources.

Highlights
  • Real radioactivity counter functionality
  • Converts phone into Geiger Müller Counter
  • Measures gamma and some beta radiation
  • Requires calibration for accuracy
  • Expert setup for precise measurements
  • Supports various iPhone and iPad models
Features
Currently charting
Read full description

RadioactivityCounter This application is a real working radioactivity counter without any extra hardware needed ! It will turn your phone into a Geiger Müller Counter to measure radioactivity after proper calibration. ** Attention after upgrading iOS to a higher iOS do the calibrate again, as camera data properties might have changed ** Disclaimer: The type of radiation picked up by the camera can be dangerous/detrimental to the user's health as well as cause damage to the device. Important note: The camera sensor can measure gamma radiation (CS137 for example) and some beta radiation (depends on the energy if the beta rays can pass through the plastic parts - for example H3 or K14 are weak sources). It cannot measure alpha rays (PO210) For AM241 though its primary a Alpha source also some gamma radiation is emitted and might be detectable for a longer measurement. Please check our homepages for examples and hints on how to measure. We did calibrations with several iPod2*, IPhone 3GS*, iPhone 4*, iPhone 4S, iPhone5, iPhone 5S iPhone 6, 6s and iPad 2, iPad 3* devices at the Helmholtz Research Centre, Munich. we used a CS137 test source from 10 µGy/h till 1 Sv/h for each of the phones we had. The values are stored for a rough start on the application (all devices differ a little bit). For precise professional measurement the devices must be adjusted to the sensor which is possible with the expert setup. For personal use the defaults should be sufficient (please give us feedback). * = Attention some phone might not be compatible due the new version of iOS or missing features (gps precision using sim cards)- please try to use an older rev of the App which should be available according to my settings (1.3).

About

Who's in Space?

Discover the current number of astronauts in orbit and their locations. Tap on an astronaut's name to access more detailed information about their mission.

Highlights
  • Real-time astronaut count
  • Astronaut location tracking
  • Detailed astronaut information
  • Data from Open Notify Astros API
  • User-friendly interface
Features
Read full description

Ever wondered who's in space? Quickly find out how many astronauts are in space and where they are during their time above Earth. Want to learn more? Simply tap an astronaut's name! Data provided by the Open Notify Astros API under the Creative Commons Attribution 3.0 Unported License (http://creativecommons.org/licenses/by/3.0/legalcode). Icon provided by Icons8 under the Attribution-NoDerivs 3.0 Unported License (https://creativecommons.org/licenses/by-nd/3.0/legalcode).

Screenshots

RadioactivityCounter2 screens
Who's in Space?4 screens

Verdict

The call

The clearest difference is price: Who's in Space? at Free against RadioactivityCounter's $4.99. Who's in Space? also leads on review sentiment (100% vs 68%) and update cadence (every 4 months vs every 15 months). RadioactivityCounter's advantage is chart position (#184 vs unranked) and ratings volume (10 vs 2). On rating, ads, in-app purchases 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

Who's in Space? is free to download; RadioactivityCounter costs $4.99 up front. Neither carries in-app purchases, so what you see is what you pay.

ReceptionRating · Positive reviews · Number of ratings

On the App Store both sit at effectively the same score — 3.1 for RadioactivityCounter against 3.0 for Who's in Space?. That said, the two scores are not equally well evidenced: RadioactivityCounter has 10 ratings behind it against 2, so its average is the more settled of the two. Written reviews are what separate them: 68% of RadioactivityCounter's written reviews are positive against 100% of Who's in Space?'s.

UpkeepUpdate frequency

RadioactivityCounter ships an update every 15 months, Who's in Space? every 4 months. The most recent releases landed on November 6, 2026 and November 1, 2026 respectively.

Scorecard7 real differences · 4 level
RadioactivityCounter versus Who's in Space?: the parameters behind the verdict, then further details
ParameterRadioactivityCounterWho's in Space?
Price$4.99Free — better
Rating3.1 (10 ratings) — better3.0 (2 ratings)
Positive reviews68.4% of reviews100.0% of reviews — better
Number of ratings10 — better2
Update frequencyEvery 15 monthsEvery 4 months — better
AdsNoNo
In-app purchasesNoNo
MonetizationPaidFree — better
Best chart rank#184 — better—
DevicesiPhone, iPodiPhone, iPad, iPod — better
Requires iOS8.0 — better13.0
Further details — not scored
Size11 MB0 MB
Age rating4+4+
DeveloperDipl.-Ing. Rolf-Dieter KleinCameron Bernhardt

Customer experience

RadioactivityCounter

All ratings10 ratings
Positive50.0%
Neutral0.0%
Negative50.0%
Written reviews19 reviews
Positive68.4%
Neutral5.3%
Negative26.3%

Who's in Space?

All ratings1 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews3 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

In-app purchases

None

RadioactivityCounter

No in-app purchases

None

Who's in Space?

No in-app purchases

Questions

Is RadioactivityCounter free?
RadioactivityCounter costs $4.99, with no in-app purchases.
Is Who's in Space? free?
Who's in Space? is free to download, with no in-app purchases.
Which has better reviews, RadioactivityCounter or Who's in Space??
RadioactivityCounter is rated higher. RadioactivityCounter averages 3.1 out of 5 from 10 ratings, while Who's in Space? averages 3.0 from 2 ratings.
Do RadioactivityCounter or Who's in Space? have ads?
Neither RadioactivityCounter nor Who's in Space? shows ads.
Which is updated more often, RadioactivityCounter or Who's in Space??
RadioactivityCounter ships an update every 15 months, and Who's in Space? every 4 months. Most recently, RadioactivityCounter was updated on November 6, 2026 and Who's in Space? on November 1, 2026.

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