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 radio remotely from your iPhone. View spectrum scope, waterfall, and access all radio controls over Wi-Fi or the internet. Supports various Icom models and includes features for ham radio operators.

Highlights
  • Spectrum scope and waterfall display
  • Full radio control
  • Remote operation over Wi-Fi/internet
  • FT8-Improved and JS8 modes
  • CW decoder and keyer
  • Speech transcription and translation
  • Logbook with ADIF import/export
Features
Read full description

Your Icom radio on your iPhone: at home over Wi-Fi or from anywhere over the internet. Made by a ham, for hams, with personal support included. SDR-Control Mobile shows the spectrum scope and waterfall of your Icom radio with all its controls. No extra hardware or software needed. WORKS WITH ■ IC-705 (Wi-Fi) ■ IC-7610, IC-7760, IC-9700, IC-7300 MK2 and the IC-R8600 receiver (radio on your network by cable) The app connects over the network only. The older IC-7300 (without MK2) has no network connection and can't be used. OPERATE ■ Spectrum scope and waterfall with band plan, DX Cluster and FT8 spots ■ Two VFOs, filters, preamp, attenuator, NB, NR, notch, AGC and more ■ Compact floating panels: tuning, PTT, CW, memories, macros, Command Bar, DTMF, RIT / ∆TX, D-Star ■ Your iPhone as microphone and speaker; the radio keeps playing in the background ■ Ready for iPhone Duo: the iPhone screens when folded, the large radio screen when open MODES ■ FT8-Improved with AutoAnswer and AutoCQ, plus the classic FT8 ■ JS8 keyboard chat ■ CW with decoder, keyer and CW keyboard ■ Speech: incoming voice transcribed and translated, your typed text sent as speech ■ SSTV, HF-Fax, APRS, WSPR and D-Star FT8-Improved, JS8, Speech and WSPR need iOS 26. TOOLS ■ Logbook with ADIF import and export, shared via iCloud with SmartSDR, FT-Control, TS-Control and K4-Control, on iPhone, iPad and Mac ■ DX Cluster, POTA, PSK Reporter, Call Lookup, Band Plan, Network Stats, Memories, Scanning ■ Controllers: MIDI, CTR2, HaliKey, Pryme, Flic ■ 4O3A Genius devices and Ultra Beam antennas MADE BY A HAM Made by Marcus, DL8MRE, who has been developing apps for Apple devices since 2009 and uses this app every day in his own shack, where all supported radios are on the desk. Personal online support and a detailed manual are included. Updates with new modes and features are free: no subscription, no in-app purchases. WHAT YOU NEED ■ One of the radios above, connected to your network ■ An iPhone with iOS 18 or later ■ For use over the internet: access to your home network from outside (see the manual) Manual: https://go-to.me/sdrcontrol-mobile-manual More apps: https://ham-radio-apps.com SDR-Control is developed independently and is not affiliated with or endorsed by Icom.

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 ratings volume (732 vs 72) and device support (3 vs 1). SDR's advantage is in-app purchases (none vs 1) and update cadence (every 2 weeks vs every 5 months). On rating, review sentiment and 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

On the App Store both sit at effectively the same score — 4.7 for Sputnik! against 4.6 for SDR. That said, the two scores are not equally well evidenced: Sputnik! has 732 ratings behind it against 72, so its average is the more settled of the two. Written reviews are what separate them: 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 November 1, 2026 and November 3, 2026 respectively.

Scorecard7 real differences · 3 level
Sputnik! versus SDR: the parameters behind the verdict, then further details
ParameterSputnik!SDR
PriceFree — better$44.99
Rating4.7 (732 ratings) — better4.6 (72 ratings)
Positive reviews92.2% of reviews — better84.3% of reviews
Number of ratings732 — better72
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 MB55 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 ratings67 ratings
Positive89.6%
Neutral0.0%
Negative10.4%
Written reviews70 reviews
Positive84.3%
Neutral5.7%
Negative10.0%

User reviews

Sputnik!

From 732 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 72 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 732 ratings, while SDR averages 4.6 from 72 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 November 1, 2026 and SDR on November 3, 2026.

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