# KSB Sonolyzer vs Scan To PDF Pro

The clearest difference is in-app purchases: KSB Sonolyzer at none against Scan To PDF Pro's 2. Scan To PDF Pro's advantage is update cadence (weekly vs every 4 months). On price, ads, device support and iOS requirement there is nothing between them.

Both are free to download. Scan To PDF Pro sells 2 in-app purchases, starting at $6.99 per month. KSB Sonolyzer asks for nothing beyond the download.

KSB Sonolyzer ships an update every 4 months, Scan To PDF Pro weekly. The most recent releases landed on October 5, 2026 and October 12, 2026 respectively.

## The numbers

| Metric | KSB Sonolyzer | Scan To PDF Pro |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 4 months | **Weekly** |
| Size | 88 MB | 1 MB |
| Requires iOS | 16.0 | 16.0 |
| Devices | iPhone, iPad | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [KSB SE & Co. KGaA](https://appshunter.io/developer/533763415) | [Marshaun Smith](https://appshunter.io/developer/1883336817) |

## What reviewers say

### KSB Sonolyzer

[App page](https://appshunter.io/ios/app/ksb-sonolyzer/id999364617)

**Features:** macOS Compatibility

**In-app purchases:** none


### Scan To PDF Pro

[App page](https://appshunter.io/ios/app/scan-to-pdf-pro-document-scan/id6760221934)

**Features:** macOS Compatibility

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Monthly Plan | $6.99 | per month |
| Yearly Plan | $39.99 | per year |


## Frequently asked questions

### Is KSB Sonolyzer free?

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

### Is Scan To PDF Pro free?

Scan To PDF Pro is free to download, with in-app purchases available.

### Do KSB Sonolyzer or Scan To PDF Pro have ads?

Neither KSB Sonolyzer nor Scan To PDF Pro shows ads.

### Which is updated more often, KSB Sonolyzer or Scan To PDF Pro?

KSB Sonolyzer ships an update every 4 months, and Scan To PDF Pro weekly. Most recently, KSB Sonolyzer was updated on October 5, 2026 and Scan To PDF Pro on October 12, 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.*