# AUDITOR app vs Hardness Conversion Master

The clearest difference is in-app purchases: AUDITOR app at none against Hardness Conversion Master's 1. AUDITOR app also leads on ads (none vs shown) and iOS requirement (13.0 vs 17.6). Hardness Conversion Master's advantage is update cadence (every 3 days vs fortnightly). On price and device support there is nothing between them.

Both are free to download. Hardness Conversion Master sells 1 one-off in-app purchase. AUDITOR app asks for nothing beyond the download.

AUDITOR app ships an update fortnightly, Hardness Conversion Master every 3 days. Both last shipped on October 5, 2026.

## The numbers

| Metric | AUDITOR app | Hardness Conversion Master |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | **No** | Yes |
| Ads | **No** | Yes |
| Update frequency | Fortnightly | **Every 3 days** |
| Size | 310 MB | 259 MB |
| Requires iOS | **13.0** | 17.6 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [HNC-Datentechnik GmbH](https://appshunter.io/developer/1472322375) | [POYU WANG](https://appshunter.io/developer/1883764660) |

## What reviewers say

### AUDITOR app

[App page](https://appshunter.io/ios/app/auditor-app/id1472322376)

**Features:** macOS Compatibility

**In-app purchases:** none


### Hardness Conversion Master

[App page](https://appshunter.io/ios/app/hardness-conversion-master/id6760411989)

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Unlock Pro | $1.99 | one-time |


## Frequently asked questions

### Is AUDITOR app free?

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

### Is Hardness Conversion Master free?

Hardness Conversion Master is free to download, with in-app purchases available.

### Do AUDITOR app or Hardness Conversion Master have ads?

Hardness Conversion Master shows ads; AUDITOR app does not.

### Which is updated more often, AUDITOR app or Hardness Conversion Master?

AUDITOR app ships an update fortnightly, and Hardness Conversion Master every 3 days. Most recently, AUDITOR app was updated on October 5, 2026 and Hardness Conversion Master on October 5, 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.*