# Resistor color decoder vs NDT Master

The clearest difference is in-app purchases: Resistor color decoder at none against NDT Master's 1. NDT Master's advantage is ads (none vs shown) and iOS requirement (15 vs 17.0). On price, update cadence and device support there is nothing between them.

Both are free to download. NDT Master sells 1 one-off in-app purchase. Resistor color decoder asks for nothing beyond the download.

Resistor color decoder ships an update every 9 days, NDT Master every 2 weeks. The most recent releases landed on November 8, 2026 and November 5, 2026 respectively.

## The numbers

| Metric | Resistor color decoder | NDT Master |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[3.0 (2 ratings)](https://appshunter.io/ios/app/ndt-master-ut-weld-calculator/id6762549446/reviews)** |
| Number of ratings | — | **2** |
| Positive reviews | — | 0.0% of reviews |
| In-app purchases | **No** | Yes |
| Ads | Yes | **No** |
| Update frequency | **Every 9 days** | Every 2 weeks |
| Monetization | — | Free with in-app purchases |
| Size | 6 MB | 20 MB |
| Requires iOS | 17.0 | **15** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Michal Pajdak](https://appshunter.io/developer/1794089424) | [雪 蔺](https://appshunter.io/developer/1853712836) |

## What reviewers say

### Resistor color decoder

[App page](https://appshunter.io/ios/app/resistor-color-decoder/id6744559438)

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

**In-app purchases:** none


### NDT Master

[App page](https://appshunter.io/ios/app/ndt-master-ut-weld-calculator/id6762549446)

This app streamlines ultrasonic testing for field inspections. It offers rapid weld rating, DAC/TCG curve building, 3D beam simulation, and OCR parameter capture. Includes essential UT calculators and material presets for efficient flaw detection and setup confidence.

**Highlights:** AWS D-Rating in 5 Seconds, DAC/TCG Curve Building, 3D Beam Simulation, OCR Parameter Capture, 9 UT Calculators, Offline-First Workflow

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Professional Unlock | $9.99 | one-time |


## Frequently asked questions

### Is Resistor color decoder free?

Resistor color decoder is free to download, with no in-app purchases.

### Is NDT Master free?

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

### Do Resistor color decoder or NDT Master have ads?

Resistor color decoder shows ads; NDT Master does not.

### Which is updated more often, Resistor color decoder or NDT Master?

Resistor color decoder ships an update every 9 days, and NDT Master every 2 weeks. Most recently, Resistor color decoder was updated on November 8, 2026 and NDT Master on November 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.*