# Frequency Analyzer vs Stackis RPN

The clearest difference is review sentiment: Stackis RPN at 100% against Frequency Analyzer's 10%. Stackis RPN also leads on rating (5.0 vs 4.5) and monetization model (free vs free with in-app purchases). Frequency Analyzer's advantage is ratings volume (166 vs 2). On price, ads, in-app purchases and device support there is nothing between them.

Both are free to download. Frequency Analyzer sells 11 in-app purchases, starting at $2.99 per 7 days and Stackis RPN sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.

Stackis RPN holds the better App Store score, 5.0 against 4.5. That said, the two scores are not equally well evidenced: Frequency Analyzer has 166 ratings behind it against 2, so its average is the more settled of the two. Written reviews point the same way: 10% of Frequency Analyzer's written reviews are positive against 100% of Stackis RPN's.

Frequency Analyzer ships an update every 8 days, Stackis RPN every 4 days. The most recent releases landed on September 26, 2026 and June 2, 2026 respectively.

## The numbers

| Metric | Frequency Analyzer | Stackis RPN |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [4.5 (166 ratings)](https://appshunter.io/ios/app/frequency-analyzer/id6468837339/reviews) | **[5.0 (2 ratings)](https://appshunter.io/ios/app/stackis-rpn/id6752929114/reviews)** |
| Number of ratings | **166** | 2 |
| Positive reviews | 10.0% of reviews | **100.0% of reviews** |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | Every 8 days | **Every 4 days** |
| Monetization | Free with in-app purchases | **Free** |
| Size | 35 MB | 10 MB |
| Requires iOS | **17.2** | 17.6 |
| Devices | iPhone | **iPhone, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Manfred Kuegel](https://appshunter.io/developer/1520736594) | [Skimra](https://appshunter.io/developer/403502071) |

## What reviewers say

### Frequency Analyzer

[App page](https://appshunter.io/ios/app/frequency-analyzer/id6468837339)

Transform your device into a professional audio analysis tool with advanced FFT analysis, SPL monitoring, and detailed visualizations. Record, analyze, and export audio data with precision calibration and multiple weighting filters.

**Highlights:** Real-time FFT analysis, Calibrated SPL measurements, 32-bit float audio recording, Synchronized video recording, Spectrogram and octave band analysis, Export WAV, CSV, images, and videos

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

**In-app purchases (11)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Frequency Analyzer Pro Weekly | $2.99 | per 7 days |
| Frequency Analyzer Pro Monthly | $3.99 | per month |
| Frequency Analyzer Pro Monthly | $3.99 | per month |
| Frequency Analyzer Pro Monthly | $4.99 | per month |
| Frequency Analyzer Pro Monthly | $4.99 | per month |
| Frequency Analyzer Pro Monthly | $4.99 | per month |
| Frequency Analyzer Pro Annual | $29.99 | per year |
| Frequency Analyzer Pro Annual | $44.99 | per year |
| Frequency Analyzer Pro Annual | $44.99 | per year |
| Frequency Analyzer Pro Annual | $44.99 | per year |
| Pro access for lifetime | $89.99 | one-time |


### Stackis RPN

[App page](https://appshunter.io/ios/app/stackis-rpn/id6752929114)

A calculator designed for users who prefer Reverse Polish Notation (RPN). It offers a familiar interface for RPN users and includes support for duodecimal calculations.

**Highlights:** RPN calculation style, Duodecimal (dozenal) support, Familiar interface for RPN users, Simple and pleasant user experience

**Features:** macOS Compatibility

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Advanced Mode | $1.99 | one-time |


## Frequently asked questions

### Is Frequency Analyzer free?

Frequency Analyzer is free to download, with in-app purchases available.

### Is Stackis RPN free?

Stackis RPN is free to download, with in-app purchases available.

### Which has better reviews, Frequency Analyzer or Stackis RPN?

Stackis RPN is rated higher. Frequency Analyzer averages 4.5 out of 5 from 166 ratings, while Stackis RPN averages 5.0 from 2 ratings.

### Do Frequency Analyzer or Stackis RPN have ads?

Neither Frequency Analyzer nor Stackis RPN shows ads.

### Which is updated more often, Frequency Analyzer or Stackis RPN?

Frequency Analyzer ships an update every 8 days, and Stackis RPN every 4 days. Most recently, Frequency Analyzer was updated on September 26, 2026 and Stackis RPN on June 2, 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.*