# Decay Tree vs CBRNResponder

The clearest difference is in-app purchases: CBRNResponder at none against Decay Tree's 2. CBRNResponder also leads on ads (none vs shown) and update cadence (weekly vs every 11 months). Decay Tree's advantage is iOS requirement (12.0 vs 15.6). On price, ratings volume and device support there is nothing between them.

Both are free to download. Decay Tree sells 2 one-off in-app purchases. CBRNResponder asks for nothing beyond the download.

CBRNResponder holds the better App Store score, 4.5 against 4.1. Both are backed by a comparable volume of ratings — 7 and 6 respectively.

Decay Tree ships an update every 11 months, CBRNResponder weekly. The most recent releases landed on October 13, 2026 and October 3, 2026 respectively.

## The numbers

| Metric | Decay Tree | CBRNResponder |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [4.1 (7 ratings)](https://appshunter.io/ios/app/decay-tree/id1066023546/reviews) | **[4.5 (6 ratings)](https://appshunter.io/ios/app/cbrnresponder/id1540310984/reviews)** |
| Number of ratings | **7** | 6 |
| Positive reviews | 100.0% of reviews | — |
| In-app purchases | Yes | **No** |
| Ads | Yes | **No** |
| Update frequency | Every 11 months | **Weekly** |
| Monetization | Free with in-app purchases | **Free** |
| Size | 53 MB | 27 MB |
| Requires iOS | **12.0** | 15.6 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Gustaf Holst](https://appshunter.io/developer/1066023545) | [Attainx Inc.](https://appshunter.io/developer/1403638152) |

## What reviewers say

### Decay Tree

[App page](https://appshunter.io/ios/app/decay-tree/id1066023546)

This educational app visually represents nuclear decay chains for various nuclides. It graphically displays decay modes and half-lives, alongside detailed tables and graphs of spin, specific activity, and emitted particles.

**Highlights:** Visualizes decay chains, Graphical display of decay modes, Graphical display of half-lives, Tabulated details of spin, specific activity, emitted particles, Graphs of spin, specific activity, emitted particles

**Features:** macOS Compatibility

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Radiation Table | $0.99 | one-time |
| Remove Ads | $1.99 | one-time |


### CBRNResponder

[App page](https://appshunter.io/ios/app/cbrnresponder/id1540310984)

This app offers free tools for logging, transmitting, storing, and analyzing environmental monitoring data. It provides a secure cloud environment for user data access and requires registration for full functionality.

**Highlights:** Environmental data logging, Data transmission capabilities, Secure cloud data storage, Data analysis tools, Data presentation features

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

**In-app purchases:** none


## Frequently asked questions

### Is Decay Tree free?

Decay Tree is free to download, with in-app purchases available.

### Is CBRNResponder free?

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

### Which has better reviews, Decay Tree or CBRNResponder?

CBRNResponder is rated higher. Decay Tree averages 4.1 out of 5 from 7 ratings, while CBRNResponder averages 4.5 from 6 ratings.

### Do Decay Tree or CBRNResponder have ads?

Decay Tree shows ads; CBRNResponder does not.

### Which is updated more often, Decay Tree or CBRNResponder?

Decay Tree ships an update every 11 months, and CBRNResponder weekly. Most recently, Decay Tree was updated on October 13, 2026 and CBRNResponder on October 3, 2026.

---

*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*