# RST Scope vs Audio SA

The clearest difference is in-app purchases: RST Scope at none against Audio SA's 1. RST Scope also leads on update cadence (every 3 days vs every 6 months). On price, ads, device support and iOS requirement there is nothing between them.

Both are free to download. Audio SA sells 1 one-off in-app purchase. RST Scope asks for nothing beyond the download.

RST Scope ships an update every 3 days, Audio SA every 6 months. The most recent releases landed on August 22, 2026 and August 31, 2026 respectively.

## The numbers

| Metric | RST Scope | Audio SA |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[5.0 (1 ratings)](https://appshunter.io/ios/app/rst-scope/id1550582276/reviews)** | — |
| Number of ratings | **1** | — |
| Positive reviews | — | 100.0% of reviews |
| In-app purchases | **No** | Yes |
| Ads | Yes | Yes |
| Update frequency | **Every 3 days** | Every 6 months |
| Monetization | **Ad-supported** | Free with in-app purchases |
| Size | 5 MB | 5 MB |
| Requires iOS | 15.6 | 15.6 |
| Devices | iPhone, iPod | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [koji kamogawa](https://appshunter.io/developer/1488210713) | [Yasuyoshi Ota](https://appshunter.io/developer/1500357652) |

## What reviewers say

### RST Scope

[App page](https://appshunter.io/ios/app/rst-scope/id1550582276)

This utility app provides spectrum scope and waterfall displays for amateur radio operators. It enhances radios lacking these features by analyzing microphone input, allowing for clear distinction of Morse code and detailed audio frequency visualization.

**Highlights:** Spectrum scope and waterfall display, Morse code distinction via FFT, Adjustable waterfall speed, Adjustable audio input level, Switchable display band (wide/narrow), Display pause function, Recording and playback of input sound

**In-app purchases:** none


### Audio SA

[App page](https://appshunter.io/ios/app/audio-sa/id6444715596)

This app analyzes audio waveforms to create visual voiceprints as TFFT images. It offers extensive customization for FFT analysis, including adjustable ranges, sizes, scales, and window functions. A simple waveform generator is also included for learning purposes.

**Highlights:** TFFT voiceprint image generation, High-resolution image export, Customizable FFT analysis settings, Adjustable audio waveform analysis range, Simple waveform generator (sine, square, noise), Multiple FFT sizes and window functions

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Remove ads. | $3.99 | one-time |


## Frequently asked questions

### Is RST Scope free?

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

### Is Audio SA free?

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

### Do RST Scope or Audio SA have ads?

Both RST Scope and Audio SA show ads.

### Which is updated more often, RST Scope or Audio SA?

RST Scope ships an update every 3 days, and Audio SA every 6 months. Most recently, RST Scope was updated on August 22, 2026 and Audio SA on August 31, 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.*