# RST Decoder Pro vs arduinoSG90

The clearest difference is price: arduinoSG90 at Free against RST Decoder Pro's $1.99. arduinoSG90 also leads on update cadence (daily vs monthly). On ads, in-app purchases, device support and iOS requirement there is nothing between them.

arduinoSG90 is free to download; RST Decoder Pro costs $1.99 up front. Neither carries in-app purchases, so what you see is what you pay.

RST Decoder Pro ships an update monthly, arduinoSG90 daily. The most recent releases landed on October 6, 2026 and October 7, 2026 respectively.

## The numbers

| Metric | RST Decoder Pro | arduinoSG90 |
| --- | --- | --- |
| Price | $1.99 | **Free** |
| Rating | **[5.0 (1 ratings)](https://appshunter.io/ios/app/rst-decoder-pro/id1521025545/reviews)** | — |
| Number of ratings | **1** | — |
| Positive reviews | 50.0% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Monthly | **Daily** |
| Monetization | Paid | — |
| Size | 1 MB | 3 MB |
| Requires iOS | 17.0 | 17.0 |
| Devices | iPhone | **iPhone, iPad** |
| Age rating | 17+ | 4+ |
| Developer | [koji kamogawa](https://appshunter.io/developer/1488210713) | [YASUYUKI INUKAI](https://appshunter.io/developer/689779927) |

## What reviewers say

### RST Decoder Pro

[App page](https://appshunter.io/ios/app/rst-decoder-pro/id1521025545)

This application decodes Morse code from your device's microphone, offering two decoding methods (BPF and FFT) with adjustable parameters. It includes features like automatic frequency detection, gain control, and real-time signal display for accurate Morse code practice and reception.

**Highlights:** Microphone Morse code decoding, BPF and FFT decoding methods, Auto Frequency Detector (AFD), Auto Gain Control (AGC), Real-time CW signal display, Waterfall display (Pro version), Adjustable control parameters

**In-app purchases:** none


### arduinoSG90

[App page](https://appshunter.io/ios/app/arduinosg90/id6482847820)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is RST Decoder Pro free?

RST Decoder Pro costs $1.99, with no in-app purchases.

### Is arduinoSG90 free?

arduinoSG90 is free to download, with no in-app purchases.

### Do RST Decoder Pro or arduinoSG90 have ads?

Neither RST Decoder Pro nor arduinoSG90 shows ads.

### Which is updated more often, RST Decoder Pro or arduinoSG90?

RST Decoder Pro ships an update monthly, and arduinoSG90 daily. Most recently, RST Decoder Pro was updated on October 6, 2026 and arduinoSG90 on October 7, 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.*