# X vs Rad Index

The clearest difference is in-app purchases: X at none against Rad Index's 1. X also leads on iOS requirement (12.0 vs 15.0). Rad Index's advantage is update cadence (fortnightly vs every 4 months). On price, ads and device support there is nothing between them.

Both are free to download. Rad Index sells 1 one-off in-app purchase. X asks for nothing beyond the download.

X ships an update every 4 months, Rad Index fortnightly. The most recent releases landed on October 5, 2026 and October 24, 2026 respectively.

## The numbers

| Metric | X | Rad Index |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 4 months | **Fortnightly** |
| Size | 79 MB | 39 MB |
| Requires iOS | **12.0** | 15.0 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [University of Oulu](https://appshunter.io/developer/1057902852) | [Simone Zen](https://appshunter.io/developer/1896760438) |

## What reviewers say

### X

[App page](https://appshunter.io/ios/app/x-ray-scatter-sim/id6463718894)

**In-app purchases:** none


### Rad Index

[App page](https://appshunter.io/ios/app/rad-index/id6770671896)

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Rad Index Premium | $8.99 | one-time |


## Frequently asked questions

### Is X free?

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

### Is Rad Index free?

Rad Index is free to download, with in-app purchases available.

### Do X or Rad Index have ads?

Neither X nor Rad Index shows ads.

### Which is updated more often, X or Rad Index?

X ships an update every 4 months, and Rad Index fortnightly. Most recently, X was updated on October 5, 2026 and Rad Index on October 24, 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.*