# ThirdCatheter vs GKAS

The clearest difference is price: GKAS at Free against ThirdCatheter's $1.99. GKAS also leads on in-app purchases (none vs 3) and iOS requirement (16.0 vs 26.0). ThirdCatheter's advantage is update cadence (every 4 days vs every 7 months). On ads and device support there is nothing between them.

GKAS is free to download; ThirdCatheter costs $1.99 up front. ThirdCatheter sells 3 in-app purchases, starting at $0.49 per month. GKAS asks for nothing beyond the download.

ThirdCatheter ships an update every 4 days, GKAS every 7 months. The most recent releases landed on September 23, 2026 and September 17, 2026 respectively.

## The numbers

| Metric | ThirdCatheter | GKAS |
| --- | --- | --- |
| Price | $1.99 | **Free** |
| Positive reviews | 100.0% of reviews | — |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | **Every 4 days** | Every 7 months |
| Monetization | Free with in-app purchases | — |
| Size | 26 MB | 9 MB |
| Requires iOS | 26.0 | **16.0** |
| Devices | iPhone, iPad | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Masaaki Hirata](https://appshunter.io/developer/942972055) | [American Dental Association](https://appshunter.io/developer/430932814) |

## What reviewers say

### ThirdCatheter

[App page](https://appshunter.io/ios/app/thirdcatheter/id1209823996)

This medical reference tool calculates the theoretical minimum diameter for guiding catheters when using three devices. It offers device data pre-installed in new versions and advanced features like net search and gap imaging evaluation in the paid version. Users are advised to consult device manuals for strategy planning.

**Highlights:** Minimum diameter calculation for guiding catheters, Pre-installed device data, Net search and gap imaging evaluation (paid), Device information sharing via AirDrop, Device data editing with CatheterEditor, Calculates space needed for device function

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

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| One Month Device Data Use | $0.49 | per month |
| 6 months Device Data Use | $1.99 | per 6 months |
| Fine-tune and save device info. | $1.99 | one-time |


### GKAS

[App page](https://appshunter.io/ios/app/gkas/id1412169340)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is ThirdCatheter free?

ThirdCatheter costs $1.99, and also offers in-app purchases.

### Is GKAS free?

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

### Do ThirdCatheter or GKAS have ads?

Neither ThirdCatheter nor GKAS shows ads.

### Which is updated more often, ThirdCatheter or GKAS?

ThirdCatheter ships an update every 4 days, and GKAS every 7 months. Most recently, ThirdCatheter was updated on September 23, 2026 and GKAS on September 17, 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.*