Comparison

Sputnik! vs SDR

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

Head to head
About

Sputnik!

Track the International Space Station and bright satellites with precise timing and location data. Get second-by-second countdowns, set reminders, and view satellite paths in the night sky. Supports offline calculations and sharing sightings.

Highlights
  • Accurate satellite and ISS sighting predictions
  • Starlink satellite train detection
  • Second-by-second countdowns
  • Sighting reminders
  • Compass direction and elevation display
  • Night sky path visualization
  • Offline calculations
Features
Read full description

Sputnik! is an easy to use tool for predicting when the International Space Station will pass by your location or when a bright satellite will be visible in the skies above. Sputnik! features: - Predictions of satellite and ISS sightings accurate to the second. - Detection of Starlink satellite trains. - Second by second countdown to the satellite sighting. - Set reminders of upcoming satellite sightings. - Displays compass direction and elevation for your device to easily find the part of the sky where the sighting will occur (requires capable device). - Rotate your device to landscape orientation to show exactly where the satellite will pass in the night sky. - Share sightings via Twitter, Facebook, Mail, Messages and others. - Automatic download of up to date satellite orbital data. - Offline calculations, no need to be connected to the internet once orbital data has been downloaded. - Input your location automatically by GPS, select from a map or enter coordinates manually. - Save your favorite places for easy access. - Audio cues for the last seconds before the satellite passes by. Sputnik! on Apple Watch: - Easily find the next and last sighting at your current location. * Sputnik! is ad-supported *

About

SDR

Control your Icom transceiver remotely or locally from your iPhone. Operate in all modes, log QSOs, and utilize integrated digital modes like FT8/FT4 and SSTV. No extra hardware is needed for global access.

Highlights
  • Remote transceiver operation
  • All mode control
  • Auto logging logbook
  • Integrated FT8/FT4 tool
  • Integrated SSTV receiver
  • Integrated CW decoder and keyer
  • DX-Cluster integration
Read full description

Software Defined Radio Client for Icom Transceivers and your iPhone SDR-Control Mobile is a full featured iPhone App to operate your Icom Transceiver at home or from around the world without additional Hard- or Software. Important: This App requires one of the following Icom Transceivers: IC-705, IC-7610, IC-9700, IC-7760 or the IC-R8600 Receiver or the new IC-7300 MK2 FACTS AND FEATURES: ■ Native iOS 26 app, backward compatible to iOS 17 ■ Compatible with any iPhone ■ Complete operation of your Icom Transceiver in all modes ■ Use the App local or to remote access of your Transceiver from any place without additional Hard- or Software ■ Logbook with auto logging, ADIF Im-/Export ■ UDP Log submission when using external logging software ■ Integrated full featured FT8 / FT4 Tool ■ Integrated SSTV receiver (NEW) ■ Integrated CW Decoder ■ Integrated CW Keyer ■ DX-Cluster integration ■ Call sign lookup integrated ■ Displays Calls on Map with heading and distance information ■ And much more... WHAT YOU NEED: - An Icom IC-705, IC-7610, IC-9700 or IC-7760 Transceiver or IC-R8600 Receiver or the new IC-7300 MK2 - The Transceiver needs to be connected to your Network (WiFi or LAN) - No USB cable needed or supported - An iPhone that runs at least iOS 17 Find out more here: https://ham-radio-apps.com Read the Manual: http://go-to.me/sdrcontrol-mobile-manual

Screenshots

Sputnik!4 screens
SDR4 screens

Verdict

The call

The clearest difference is price: Sputnik! at Free against SDR's $44.99. Sputnik! also leads on rating (4.7 vs 4.5) and ratings volume (731 vs 64). SDR's advantage is in-app purchases (none vs 1) and update cadence (every 2 weeks vs every 5 months). On ads 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

Sputnik! is free to download; SDR costs $44.99 up front. Sputnik! sells 1 one-off in-app purchase. SDR asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

Sputnik! holds the better App Store score, 4.7 against 4.5. That said, the two scores are not equally well evidenced: Sputnik! has 731 ratings behind it against 64, so its average is the more settled of the two. Written reviews point the same way: 92% of Sputnik!'s written reviews are positive against 84% of SDR's.

UpkeepUpdate frequency

Sputnik! ships an update every 5 months, SDR every 2 weeks. The most recent releases landed on October 15, 2026 and October 11, 2026 respectively.

Scorecard9 real differences · 1 level
Sputnik! versus SDR: the parameters behind the verdict, then further details
ParameterSputnik!SDR
PriceFree — better$44.99
Rating4.7 (731 ratings) — better4.5 (64 ratings)
Positive reviews92.2% of reviews — better84.1% of reviews
Number of ratings731 — better64
Update frequencyEvery 5 monthsEvery 2 weeks — better
AdsNoNo
In-app purchasesYesNo — better
MonetizationAd-supported — betterPaid
DevicesiPhone, iPod, Apple Watch — betteriPhone
Requires iOS14.0 — better17.6
Further details — not scored
Size35 MB47 MB
Age rating4+4+
DeveloperApplicate LtdMarcus Roskosch

Customer experience

Sputnik!

All ratings731 ratings
Positive94.8%
Neutral2.6%
Negative2.6%
Written reviews243 reviews
Positive92.2%
Neutral1.2%
Negative6.6%

SDR

All ratings64 ratings
Positive89.1%
Neutral0.0%
Negative10.9%
Written reviews69 reviews
Positive84.1%
Neutral5.8%
Negative10.1%

User reviews

Sputnik!

From 731 App Store ratings

What we love

  • 🚀 Accurate satellite tracking
  • 👍 Easy to use interface
  • 🔭 Supports tracking of various satellites (ISS, Hubble, Starlink)
  • ⏰ Provides countdown and reminders for sightings

Room to improve

  • 🐛 App not working/crashing for some users
  • 🔍 Unclear information about satellite visibility (e.g. what 'enters Earth's shadow' means)
  • 🔧 Difficulty updating satellite data
  • 🙈 Dark mode text visibility issues

SDR

From 64 App Store ratings

What we love

  • 🚀 Works perfectly with ICOM radios
  • 👍 Intuitive and easy to use
  • 🌟 Feature-rich and comprehensive
  • 💯 Stable and reliable performance
  • 📱 Great for remote operation

Room to improve

  • 🐛 FT8 decoding issues (lower signal levels)
  • 🐛 Dialogs do not scale with larger text setting
  • 🐛 UI elements can be cramped on iPhone
  • 🐛 Some buttons are small and hard to press
  • 🐛 Frequency display overlaps buttons

Bugs and requests

Sputnik!

Reported bugs

3 issues
  • App reporting 'No Sightings' for all categories
  • Null check errors when selecting satellite sightings
  • Issues with location settings and data updates

Requested features

4 requests
  • Add support for more satellite types
  • Improve sky chart visualization and orientation
  • Provide filtering options (e.g. by elevation, magnitude)
  • Implement automatic data updates

SDR

Reported bugs

12 issues
  • Dialogs do not scale with larger text setting
  • Frequency display overlaps buttons
  • FT8 decoding issues (lower signal levels than WSJTX)
  • App crashes and leaves radio in transmit
  • Logbook export not functional after update
Show 7 more
  • Function button for horizontal scrolling not fully displayed
  • FT8 decode is useless and unreliable
  • Messed up radio, requiring reset
  • RX audio unusable outside home network (prior to 1.5.1)
  • Struggles with audio RX packets on remote cellular networks
  • Cannot work over mobile data with certain carriers (EE)
  • FT8 alerts sound but don't display

Requested features

14 requests
  • Develop for IC-7800
  • CarPlay support
  • Apple Watch add-on
  • Windows version
  • JS8call support
Show 9 more
  • More digital modes
  • Display memory bank names
  • Initiate memory scan from app
  • WSPR implementation
  • Tool for WSPR
  • More FT8/FT4 features (e.g., setting transmit frequency directly in FT8 view)
  • Send image to unit
  • KISS TNC support
  • Control digital modes (reflectors, etc.)

In-app purchases

1 purchases

Sputnik!

One-time1
  • Go ad-free$0.99
None

SDR

No in-app purchases

Questions

Is Sputnik! free?
Sputnik! is free to download, with in-app purchases available.
Is SDR free?
SDR costs $44.99, with no in-app purchases.
Which has better reviews, Sputnik! or SDR?
Sputnik! is rated higher. Sputnik! averages 4.7 out of 5 from 731 ratings, while SDR averages 4.5 from 64 ratings.
Do Sputnik! or SDR have ads?
Neither Sputnik! nor SDR shows ads.
Which is updated more often, Sputnik! or SDR?
Sputnik! ships an update every 5 months, and SDR every 2 weeks. Most recently, Sputnik! was updated on October 15, 2026 and SDR on October 11, 2026.

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